Synthesis and Reactivity of Copper(I) and Iron(II) CarboxylateBridged Dimetallic Complexes
by
Daniel D. LeCloux
B.S., University of Minnesota- Twin Cities (1992)
SUBMITTED TO THE DEPARTMENT OF CHEMISTRY IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY IN CHEMISTRY
AT THE
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
February 1998
© Massachusets Institute of Technology, 1998
All rights reserved
Signature of Author:.
Department of Chemistry
February 11, 1998
Certified by:
'Stepen !Aippard
Thesis Supervisor
Accepted by:
Dietmar Seyferth
Chairman, Departmental Committee on Graduate Studies
MASSACHUSETTS INSTITUTE
OF TECHNOLOGY
JUN 15 1998
LIBRARIES
This doctoral thesis has been examined by a Committee of the
Department of Chemistry as fre-, ...
Christopher C. Cummins
Professor of Chemistry
Committee Chairman
U
V
' Stephen
J. Lippard
Arthur Amos Noyes Chair and Professor of Chemistry
Thesis Supervisor
(N
3 /
Daniel G. Nocera
Professor of Chemistry
Synthesis, Characterization and Reactivity of Copper(I) and Iron(lI) Bis(carboxylate)Bridged Complexes
by
Daniel D. LeCloux
Submitted to the Department of Chemistry on February 11, 1998, in partial
fulfillment of the requirements for the Degree of Doctor of Philosophy.
Abstract
Chapter 1. Synthesis and Characterization of a Novel Class of Dicopper(I)
Bis(carboxylate)-Bridged Complexes
The syntheses, spectroscopic properties, crystal and molecular structures, and
bonding of several dicopper(I) bis(carboxylate)-bridged complexes are described in
which the bridging dicarboxylate ligand is the dianion of m-xylylenediamine
bis(Kemp's triacid imide) (H2XDK, 1). A sterically demanding benzyl derivative of
H 2 XDK was prepared, H 2BXDK (6). Reaction of these two ligands as well as the
propyl analog, H 2PXDK (2), with thallium ethoxide provided dithallium salts T12L
(L = XDK, 7; PXDK, 8; and BXDK, 9). Reaction of 7, 8, or 9 with excess CuBr(Me 2S) in
CH 2Cl 2 /MeCN afforded dinuclear acetonitrile adducts [Cu 2L(MeCN)] (L = XDK, 10;
PXDK, 11; and BXDK, 12) in high yield and multigram quantities. The coordination
chemistry of the Cu 2 (XDK) platform was explored with a range of ancillary ligands.
Treatment of 10, 11, or 12 with an excess of the specified neutral donor ligand
provided complexes [Cu 2 (XDK)(PPh 3 )2 ] (13), [Cu 2 (XDK)(2,6-Me 2PhNC) 3 ] (14a),
[Cu2(XDK)(g-2,6-Me 2PhNC)(2,6-Me 2PhNC) 2 ] (14b), [Cu 2 (XDK)(NB) 2 ] (15, NB =
norbornene), [Cu 2 (XDK)(tmeda)] (17), [Cu 2(PXDK)(tmeda)] (18), [Cu 2 (BXDK)(tmeda)]
(19), and [Cu(4,4'-Me 2bpy) 2 ][Cu(XDK)] (20). Reaction of 10 with an excess of
cyclohexene resulted in the loss of the acetonitrile ligand, affording the parent
unsubstituted complex [Cu 2(XDK)] (16). Attempts to prepare anionic carbon-bridged
dicopper(I) complexes with alkyl or aryl lithium compounds or cyanide reagents
resulted instead in extraction of one of the Cu(I) ions, affording (Et 4N)[Cu(PXDK)]
(21) and [CuLi(XDK)(THF) 2] (22). Crystallographic chemical analysis of the complexes
revealed linear two-coordinate, trigonal three-coordinate, and pseudotetrahedral
four-coordinate copper(I), depending upon the composition, and variable degrees of
Cu-Cu bonding (dcu-cu range, 2.5697(8)-3.4211(6) A).
Chapter 2. Synthesis and Characterization of Cu(I)-Cu(II)
M(II) Heterodimetallic Bis(carboxylate-bridged)
Electrochemical, and Spectroscopic Investigations
The synthesis, spectroscopic, electrochemical, and
series of Cu(I)Cu(II) bis(carboxylate-bridged) complexes
Mixed-Valence and Cu(I)Complexes: Structural,
structural properties of a
are described, as well as
related investigations with Cu(I)M(II) (M = Fe and Zn) analogs, utilizing the
dianionic m-xylylenediamine bis(Kemp's triacid imide) ligand system. Treatment of
previously reported [Cu 2 (XDK)(MeCN)] (1) or [Cu2(PXDK)(MeCN)] (2, PXDK = the
propyl derivative of XDK) with one equivalent of silver(I) triflate, trifluoroacetate,
or tetrafluoroborate in THF afforded mixed valence complexes [Cu2L(A-X)(THF) 2] (X
= triflate, L = XDK, 4, or PXDK, 5; X = trifluoroacetate and L = XDK, 6); or
[Cu 2 L(THF) 4 ]X (X = tetrafluoroborate, L = XDK, 7, or PXDK, 8). Complex 8 was also
prepared from equimolar (Et 4 N)[Cu(PXDK)] (3) and copper(II) triflate. Solid state
structural investigations on 4, 6, and 8 revealed symmetric square pyramidal
coordination environments about each copper atom and short Cu-Cu distances
ranging from 2.3988(8)-2.4246(12) A., features which taken together imply significant
metal-metal bonding character. The nature of the Cu-Cu bonding in this series of
complexes was further interrogated by (a) comparative structural and ligand
exchange studies with mixed-metal analogs [CuZn(PXDK)(OTf)(THF) 2 (H 20)] (9),
[CuFe(PXDK)(OTf)(NB)MeCN)] 2 (10a, NB = norbornene), and CuZn(PXDK)(OTf)(NB)(H 2 0) (11), all of which exhibited longer metal-metal distances ranging from
3.294(2)-3.732(2) A and monodentate, terminal triflate ligation; (b) by variable
temperature and field EPR studies, which showed that complexes 4-8 possess a fully
delocalized electronic structure in the solid state and solution down to liquid
helium temperatures; and (c) by molecular orbital calculations on simplified models
of 4-8, which revealed a Cu-Cu bonding interaction in the SHOMO and SOMO,
comprised mainly of a-type overlap between the dx2-y2 orbitals. In addition, complex
4 was shown by cyclic voltammetry to under go a chemically reversible and
electrochemically quasireversible one-electron reduction that is markedly positive
for a Cu(I)Cu(II) complex with an all-oxygen, dianionic donor set. Overall, we
provide definitive evidence that, utilizing the XDK scaffold, an unusual series of
class m mixed-valence dicopper complexes has been accessed. These studies should
aid in understanding an electronically similar Cu-Cu bonded system at the
biological CuA site.
Chapter 3. Preparation of Sterically Hindered Diiron(II) Tetracarboxylate Complexes,
and Their Reactivity Toward Dioxygen
A family of diferric peroxo-bridged complexes has been prepared which
matches exactly the combination of carboxylate and imidazole donors of the Hperoxo
intermediate in sMMO. A variety of methods including UV-Vis, EPR, Resonance
Raman, and M6ssbauer spectroscopies have been employed to elucidate their
structures. These adducts have inequivalent iron coordination environments, a
feature which is attributed either to an asymmetric peroxide bridge, a
disproportionate arrangement of the ancillary carboxylate and nitrogen donor
ligands about each iron center, or a combination of the two. Kinetic studies revealed
that the rate of peroxo formation is first order in diiron(II) complex and 02,
implicating a rate-determining bimolecular collision between the reaction
components. Moreover, the rate of peroxo formation tracks inversely with the steric
demands of the carboxylate substituents, implying that a carboxylate shift is
associated with the rate-determining step. The oxygenation rate is affected much
more dramatically by the basicity of the N-donor ligand, however, with a difference
of >10 5 s -1 noted for the pseudo-first-order rate constants with 1-alkylimidazole
versus pyridine ligation.
Chapter 4. Biomimetic Oxidation Studies With Discrete Diiron(III) Bis(carboxylate)Bridged Peroxo Complexes: Toward Functional Models of Oxygen Intermediates of
Soluble Methane Monooxygenase
The reactivity properties of two diiron(III) peroxo complexes have been fully
elucidated. These adducts behave as nucleophilic/basic peroxides, exhibiting no
propensity to serve as oxygen atom donors for even potent acceptors such as
triphenylphosphine. The 1-butylimidazole ligands in 1 enhance the
nucleophilicity/basicity of the peroxo compared to the pyridine analog, probably
because the former ligand is a superior a-donor. This feature imparts more electron
density to the iron centers, which in turn is transmitted to the peroxo ligand.
Thermolysis of the peroxo adducts in a variety of media results in solvent oxidation,
providing ketone and alcohol products in modest yield based on the complex. A
detailed analysis of cyclopentane oxidation provided evidence for a radical chain
autoxidation mechanism, a reactivity manifold which does not mimic the
hydrocarbon oxidation chemistry of sMMO.
Thesis Supervisor: Stephen J. Lippard
Title: Arthur Amos Noyes Professor of Chemistry
This thesis is dedicated to my family for all your love, support and patience,
and in memory of my grandfather, Roland C. LeCloux.
Acknowledgments
I write this section of my thesis with the utmost pleasure, not only because I
have saved it for last, but more importantly, it also gives me the opportunity to
thank all those that have helped to make my experience at MIT so professionally
and personally rewarding. First and foremost I would like to thank my advisor,
Steve Lippard, for giving me virtually complete freedom to develop my research
projects, while constantly instilling in me the fundamentals of scientific thinking,
writing, and presentation. Former Lippard group members have reminded me how
much I will value having acquired these skills once I pursue an independent career.
I must say that I came to appreciate all of them when writing the thesis, and I know
they will serve me well in the future, whatever that may hold.
I also must acknowledge my undergraduate advisor, William B. Tolman, at
the University of Minnesota-Twin Cities. I first met Bill when taking his
introductory organic chemistry course as a junior. At the time I was very committed
to going to medical school, but I had enjoyed the subject immensely and wanted to
obtain some practical lab experience. He enthusiastically agreed to allow me to work
in his lab, and over the next two years helped to instill in me a love for chemistry
which I will never relinquish. Needless to say the thought of medical school soon
thereafter became a distant memory. Bill continues to provide me with much
practical advice concerning all facets of my career, and he is a great friend.
There seems to be a countless number of colleagues that I need to thank for
helping me professionally over the past five years. When I first arrived, fellow
Subgroup 5 members Linda Doerrer, Joanne Yun, Tomoaki Tanase, and Jackie Acho
helped get me started in lab. Laura Pence taught an anxious and often times
overbearing young graduate student the basics of X-ray crystallography; her
knowledge and patience are much appreciated. Although I never worked with him
directly, Andrew Feig was always willing to answer my questions and to engage in
spirited scientific debates, both of which are necessary for building the enthusiasm
and confidence of a young student.
Many helped to bring together the stories described in these thesis chapters.
Mike Scott and Peter Fuhrmann were always there to aid with difficult X-ray
structures. Dave Coufal kindly ran liquid helium EPR samples for me, since I was
always a tad too lazy to learn how to use the instrument. Maria Bautista and Linda
Doerrer taught me some of the finer points of cyclic voltammetry and high vacuum
line techniques. Marc Johnson and Mike Fickes of the Cummins group helped with
the MO calculations, and Mike also ran several high field, variable temperature
NMR experiments for me. Kathy Franz acquired SQUID magnetic data on the
copper complexes. Amy Barrios helped with many Resonance Raman studies. Jack
Mizoguchi and Dongwhan Lee devoted many hours to my M6ssbauer samples over
at Northeastern. Ann Valentine cheerfully taught me the joys of low-temperature,
stopped-flow UV-vis spectroscopy and GC-MS. Dietrich Steinhuebel always
provided an extra steady pair of hands for preparing thermally unstable peroxo
samples. Finally, I thank Mike Fickes, Ann Valentine, Dietrich Steinhuebel, and
Justin Du Bois for a countless number of enlightening scientific discussions. I have
learned much from each one of them concerning my research and chemistry in
general.
Of course my personal experiences at MIT are inextricably tied to professional
ones, so there will be quite a bit of repetition here. As I have preached over the years
to just about anyone who will listen to me, I firmly believe single greatest attribute
of MIT is one's colleagues, as they must be one of the brightest collections of people
anywhere, and many in the chemistry department have become my very close
friends. First I would like to thank the entire Lippard group. You are a wonderfully
bright, enthusiastic, and fun-loving bunch that always seemed to put up with my
intense, although good-hearted, demeanor. For this and all of the fun we had
outside of the lab, I am very grateful. In addition, I must give a special thank you to
Ann Valentine for being a great friend over our years at MIT, and in particular for
helping me get through the thesis writing process. Everyone needs to be able to
share this equally euphoric and frustrating experience with someone, lest go insane,
and you certainly provided that for me. Finally, there are "the guys", as Jonas Peters
has dubbed us, which includes Jonas, Mike Fickes, Robert Baumann, and Dietrich
Steinhuebel. I must also throw Seble Wagaw in there as a ceremonial member, since
she too has partaken in our escapades with much enthusiasm. I am confident that
our paths will cross again on many occasions in the future, yet I will greatly miss
our time at MIT.
9
Table of Contents
Ab stract............................................................................
......................................... 3
D ed ication ..................................................................
.............................................. 6
Acknowledgements..................................................................................................7
Table of C ontents ................................................ ................................................... 9
List of T ables.............................................................. .............................................. 12
L ist of Schem es ........................................................... ............................................ 14
List of Figures............................................................ .............................................. 15
Chapter I. Synthesis and Characterization of a Novel Class of
Dicopper(I) Bis(carboxylate)-Bridged Complexes ....................................
... 19
In trod u ction ..............................................................
.............................................. 20
Experim ental Section ....................................................
........................................ 22
General Considerations ....................................................
22
Physical Measurements ....................................................
22
Syn th esis ........................... ........................................................................... 23
Collection and Reduction of X-ray Data.................................
.... 33
Results and D iscussion ....................................................................... .................. 35
Ligand Synthesis ....................................................................... ................. 35
Preparation and Reactivity of Dicopper(I) Bis(carboxylate)Bridged C om plexes ....................................................................................
37
C onclu sions....... . .....................................................................................................
46
A cknow ledgem ent ............................................................................ .................... 46
References and N otes.................................................... ........................................ 47
Chapter II. Synthesis and Characterization of Cu(I)-Cu(II) MixedValence and Cu(I)-M(II) Heterodimetallic Bis(carboxylatebridged) Complexes: Structural, Electrochemical, and
Spectroscopic Investigations................................................................................86
In tro d u ction ..............................................................
.............................................. 87
Experim ental Section ......................................................................... ................... 90
General Considerations ....................................................
90
Physical Measurements ....................................................
91
Extended HUickel Molecular Orbital Calculations........................... 92
Preparation of Compounds ..................................... .............
92
Collection and Reduction of X-ray Data.................................
.... 95
Results and Discussion ........................................................................ ................. 96
10
Preparation and Structural Characterization of MixedValence Complexes .......................................................
97
Preparation and Structural Characterization of
Heterodimetallic Complexes ................................................. 100
Electrochemical Properties of the Mixed-Valence
C om plexes ........................................................ ........................................... 103
EPR Studies ............................................................................ ..................... 106
Molecular Orbital Calculations ............................................... 108
C onclusions....... . .....................................................................................................
110
A cknow ledgem ent ........................................................................... ..................... 111
References and Notes.................................................... ........................................ 112
Chapter III. Modeling the Hperoxo Intermediate of Soluble
Methane Monooxygenase: Preparation of Sterically Hindered
Diiron(II) Tetracarboxylate Complexes, and Their Reactivity
Tow ard D ioxygen .........................................................
...........................................
159
Introduction .............................................................. .............................................. 160
Experim ental Section .................................................... ........................................ 165
General Considerations ..................................... ...............
165
..... 166
Synthesis ....................................................................................................
Collection and Reduction of X-ray Data................................................170
Physical Measurements............................................................................171
Results and D iscussion ............................................................................................
175
Preparation and Characterization of Complexes ................
175
Reactions of the Diferrous Complexes Toward Dioxygen ................... 178
EPR and 1H NMR Studies..............................................
181
Resonance Raman Studies of the Peroxo Adducts............................
181
M6ssbauer Spectroscopy...........................................
..................... 183
Kinetic Studies of the Reaction of the Diferrous
Complexes With 02 and a Proposed Mechanism for
Peroxo Form ation ..................................................................................
....... 185
C onclusions...................................................................................................................
188
A cknow ledgem ent ........................................................................... ..................... 188
References and Notes.................................................... ........................................ 190
Chapter IV. The Reactivity of Well Defined Diiron(III) Peroxo
Complexes Towards Substrates: Addition to Electrophiles and
Hydrocarbon Oxidation .......................................................................................
244
11
Introduction ............................................................................................................ 245
Experimental Section............................................................................................246
General Considerations ..................................... ...............
246
Physical Measurements .............................................................................. 247
Synthetic Methods.....................................................
...................... 248
Intermolecular Kinetic Isotope Measurements .................................... 250
Results and Discussion ......................................................................................... 250
Reactions of Peroxide Complexes 1 and 2 With Various
Reagents at -77 C ....................................................................................... 250
Thermolysis Reactions Leading to Solvent Oxidation ......................... 254
C onclusions................................................................................................
................. 260
References and Notes............................................................................................261
Biographical Note .................................................................................................. 284
List of Tables
..
51
Table 1.1. Summary of X-ray Crystallographic Data .......................
Table 1.2. Selected Bond Distance and Angles...................................53
Table 1.3. Atomic Coordinates and Equivalent IsotropicThermal
Parameters for H 2(BXDK) (6)...........................................56
Table 1.4. Atomic Coordinates and Equivalent Isotropic Thermal
Parameters for [Cu 2 (XDK)(MeCN)] (10) ...............................................
58
Table 1.5. Atomic Coordinates and Equivalent Isotropic Thermal
Parameters for [Cu 2 (XDK)(PPh 3)21 (13) ...................................... 60
Table 1.6. Atomic Coordinates and Equivalent Isotropic Thermal
Parameters for [Cu 2 (XDK)(2,6-Me 2C6H 3NC) 3] (14a) .......................... 63
Table 1.7. Atomic Coordinates and Equivalent Isotropic Thermal
Parameters for [Cu 2 (XDK) (ji-2,6-Me 2C6H 3NC)(2,665
Me 2C6H 3NC) 2] (14b) ....................................
Table 1.8. Atomic Coordinates and Equivalent Isotropic Thermal
Parameters for [Cu 2 (XDK)(NB) 2] (15)................................................. 67
Table 1.9. Atomic Coordinates and Equivalent Isotropic Thermal
...... 69
Parameters for [Cu2(XDK)12 (16)..................................
Table 1.10. Atomic Coordinates and Equivalent Isotropic
Thermal Parameters for [Cu 2(XDK)(tmeda)] (17)..........................72
Table 1.11. Atomic Coordinates and Equivalent Isotropic
Thermal Parameters for (Et 4N)[Cu(XDK)] (21) ................................... 74
Table 1.12. Atomic Coordinates and Equivalent Isotropic
Thermal Parameters for [CuLi(XDK)(THF)21 (22) .............................. 77
Table 2.1. Summary of pertinent spectroscopic and structural
data on known class III mixed-valence copper systems ................ 117
Table 2.2. Summary of X-ray Crystallographic Data .................................... 118
Table 2.3. Selected Bond Distances and Angles ....................................... 119
Table 2.4. Atomic coordinates (x 104) and equivalent isotropic
121
displacement parameters (A2 x 103) for 4 ............................................
Table 2.5. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 6 ............................................
123
Table 2.6. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 8 ............................................
125
Table 2.7. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 9 .................................... 127
Table 2.8. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 11 ..........................................
Table 2.9. Selected electrochemical data for a range of copper
redox couples ........................................................
Table 2.10. EPR g values and copper hyperfine coupling constants
for 7 ..............................................................................................................
Table 3.1. Summary of data acquired for selected RR and sMMO
m odel complexes............................................ ...................................
Table 3.2. Summary of X-ray Crystallographic Data .....................................
Table 3.3. Selected Bond Distances and Angles ..................................................
Table 3.4. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 6 ............................................
Table 3.5. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 7 ............................................
Table 3.6. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 12 ..........................................
Table 3.7. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 13 ..........................................
Table 3.8. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 16 ..........................................
Table 3.9. Effect of ligand steric and electronic properties and
solvent on stable peroxo adduct formation................
Table 3.10. Manometric studies of the dioxygen uptake for 13, 16,
and [Fe(Tp 3,5-iPr 2)(O2CH 2Ph)] vs. equimolar Vaska's
complex...................................................... ..........................................
Table 3.11. A summary of resonance Raman data obtained for
the peroxo adducts............................................................. ................
Table 3.12. M6ssbauer parameters for the peroxo adducts ..............................
Table 3.13. Summary of kinetic data for the reaction of the
diferrous complexes with oxygen at -77 'C ....................................
Table 4.1. A summary of reagents and solvents used for the
stoichiom etric reactions .......................................................................
Table 4.2. A survey of solvent oxidation reactions mediated by
peroxo 1...................................................... ..........................................
Table 4.3. Cyclopentane oxidation reactions carried out with
peroxo 1...................................................... ..........................................
129
131
132
194
195
196
199
202
205
208
212
215
216
217
218
219
264
265
266
14
List of Schemes
Schem e
Schem e
Schem e
Schem e
Schem e
Schem e
1.1 ..................................................................
................
1.2 .....................................................................................................................
2.1 ............................................................... ................................................
3.1 ............................................................... ................................................
3.2 ............................................................... ................................................
4.1 ............................................................... ................................................
79
80
133
220
221
267
List of Figures
Figure 1.1. ORTEP (50% thermal ellipsoids) and space-filling
diagrams of H 2BXDK (6) ........................................
...... 81
Figure 1.2. ORTEP diagram of [Cu 2(XDK)(MeCN)] (10) with 50%
therm al ellipsoids.......................................... .................................. 82
Figure 1.3. ORTEP diagrams with 50% thermal ellipsoids for
(clockwise from top left) [Cu 2 (XDK)(PPh 3)2] (13),
[Cu 2(XDK)(2,6-Me 2PhNC) 3] (14a), [Cu 2 (XDK)(p-2,6Me 2 PhNC)(2,6-Me 2PhNC) 21 (14b), and
83
[Cu 2 (XDK)(NB) 2 ] (15) .................................... ..............
Figure 1.4. ORTEP diagrams with 50% thermal ellipsoids for
(clockwise from top left) [Cu2(XDK)]2 (16),
[Cu 2(XDK)(tmeda)] (17), (Et 4N)[Cu(PXDK)] (21), and
[CuLi(XDK)(THF) 2] (22) ................................................ 84
Figure 2.1. Electronic absorption spectrum of [Cu 2 (XDK)(g.... 134
OTf)(THF) 2] (4), 0.74 mM in THF...................................
Figure 2.2. Electronic absorption spectrum of [Cu 2 (XDK)(gi0 2CCF3)(THF) 2] (6), 0.74 mM in THF....................................135
Figure 2.3. Electronic absorption spectrum of
[Cu 2(XDK)(THF) 4](BF4) (7), 0.47 mM in THF .................................... 136
Figure 2.4. Conductivity plots for [Cu 2(XDK)(g-OTf)(THF) 2] (4)
and Bu 4 NPF 6 in THF at 296 K........................................................... 137
Figure 2.5. Conductivity plots for [Cu 2 (XDK)(THF)4](BF 4) (7) in
.... 138
THF and Bu4 NPF6 in THF at 296 K...................................
Figure 2.6. ORTEP diagram of [Cu 2 (XDK)(g-OTf)(THF) 2] (4) with
139
50% thermal ellipsoids .................................... ............
Figure 2.7. ORTEP diagram of [Cu 2(XDK)(ji-O 2CCF3)(THF) 2] (6)
with 50% thermal ellipsoids.......................................140
Figure 2.8. ORTEP diagram of [Cu 2(PXDK)(THF) 4](BF 4 ) (8) with
50% thermal ellipsoids ............................................... 141
Figure 2.9. (Top) Stacked IR spectra of 10a and 10b in the
carboxylate-vco and the triflate-vso regions.................142
Figure 2.10. ORTEP diagram of [CuZn(PXDK)(OTf)(THF) 2(H20)]
...... 143
(9) with 50% thermal ellipsoids..................
Figure 2.11. ORTEP diagrams of [CuZn(PXDK)(OTf)(NB)(H 20)]
.................................................. 144
(11) with 50% thermal ellipsoids.
Figure 2.12. Cyclic voltammogram of 10 mM [Cu 2(XDK)] in THF ................ 145
Figure 2.13. Plot of anodic and cathodic currents versus (scan
speed)1/ 2 for [Cu 2 (XDK)] ....................................
146
Figure 2.14. Cyclic voltammogram of 10 mM
[Cu 2(XDK)(THF) 4](BF 4 ) (7) in THF ................................................... 147
Figure 2.15. Plot of anodic and cathodic currents versus (scan
148
speed) 1/ 2 for [Cu 2 (XDK)(THF)4](BF 4) (7) .............................................
Figure 2.16. Cyclic voltammogram of 10 mM [Cu 2 (XDK)(gOTf)(TH F) 2] (4) in TH F........................................................................ 149
Figure 2.17. Plot of anodic and cathodic currents versus (scan
150
speed) 1/ 2 for [Cu 2 (XDK)(g-OTf)(THF) 2] (4) ..................................
(XDK)(g[Cu
mM
of
10
voltammogram
Cyclic
2.18.
Figure
2
151
OTf)(THF) 2] (4) in THF................................. ..............
Figure 2.19. Cyclic voltammogram of 10 mM [Cu 2 (XDK)(p0 2CCF3)(THF) 2] (4) in THF............................................152
Figure 2.20. X-band EPR spectra of 1 mM [Cu 2(XDK)(THF) 4 ](BF 4)
(7) as a frozen solution at 77 and 9 K, along with a
....................................... 153
sim ulation ..................................................
Figure 2.21. X-band EPR spectra of [Cu 2(XDK)(THF) 4](BF 4) (7) as a
powdered solid at 296, 77, and 9 K, along with a
....................................... 154
sim ulation ..................................................
Figure 2.22. Q-band EPR spectrum of [Cu 2 (XDK)(THF) 4](BF4) (7) .................... 155
Figure 2.23. Contour plots derived from extended Hiickel
calculations for the SOMO of [Cu2(0 2CCH3)2(OM e2)4]...................................................................................156
Figure 2.24. Contour plot derived from extended Hiickel
calculations for the SHOMO of [Cu2(157
2CCH3)2 (OM e2)4 ]...................................................................................
Figure 2.25. Fragment molecular orbital diagram and a Walsh
158
diagram for [Cu 2(OH)2 (OH2)2(OMe2)4] ...............................................
Figure 3.1. Chemdraw representations of the active site
structures of: (A) reduced R2, (B) reduced MMOH
222
(Hred), and (C) oxidized MMOH (Hox) ....................................
Figure 3.2. A summary of the ribonucleotide reductase and
sMMO catalytic cycles ................................................. 223
Figure 3.3. ORTEP diagram of [Fe2 (BXDK)(p-O2Ctert-Bu)(O2CtertBu)(py)2] (6) with 50% thermal ellipsoids............................224
Figure 3.4. Space-filling models of [Fe 2 (PXDK)(O 2Ct-Bu)(9p-O 2CtBu)(Me-Im)2] and [Fe 2(BXDK)(O 2Ct-Bu)(gC-O 2CtBu)(py )2] (6)...................................................................... .................. 225
Figure 3.5. ORTEP diagram of [Fe 2(XDK)(gO2CPhCy)(O 2CPhCy)(py)21 (7) with 50% thermal
ellipsoids ......................................................................... ................... 226
Figure 3.6. Space-filling representation of [Fe 2(XDK)(p.227
O2CPhCy)(O 2CPhCy)(py)2] (7) ...............................................
Figure 3.7. ORTEP diagram of [Fe 2(XDK)(gO2CPhCy)(O2CPhCy)(py)2] (7) with 50% thermal
ellip soid s.................................................... ........................................ 228
Figure 3.8. ORTEP diagram of [Fe 2(BXDK)( -0 2 CPh)(0 2CPh)(py) 2 1
(12) with 50% thermal ellipsoids ....................................
.... 229
Figure 3.9. ORTEP diagram of [Fe 2(BXDK)(g02CPhCy)(02CPhCy)(py) 2] (13) with 50% thermal
ellipsoids ......................................................................... ................... 230
Figure 3.10. ORTEP diagram of [Fe 2 (PXDK)(ji02PhCy)(02PhCy)(Bu-Im) 2] (16) with 50% thermal
ellipsoids ......................................................................... ................... 231
Figure 3.11. A schematic illustration of the effect of ligand
substituent steric repulsion on the orientation of the
bridging ancillary carboxylate....................................232
Figure 3.12. Representative UV-Vis spectra for the reaction of
diferrous complexes 6-15 with 02 at -80 C ................................... 233
Figure 3.13. Resonance Raman spectra obtained with 647 nm
excitation on fluid toluene solutions (-80 °C) of: (A)
[Fe 2(160 2)(PXDK)(O 2CPhCy) 2(Bu-Im)2] (16.1602), (B)
[Fe 2(180 2 )(PXDK)(O 2CPhCy) 2(Bu-Im) 2] (16.1802), and
toluene ........................................................................... .................... 234
Figure 3.14. Solvent subtracted resonance Raman spectra ................................. 235
Figure 3.15. (A) Resonance Raman spectrum obtained with 647
nm excitation on a fluid toluene solution (-80 oC) of
[Fe 2(O2)(PXDK)(O 2CPhCy)2 (Bu-Im)2] (16O02), prepared
from 16 and a 1:2:1 mixture of 1602, 160180, and 1802.
Figure
Figure
Figure
Figure
Figure
Figure
Figure
Figure
(B) Toluene solvent background subtracted from the
spectrum in A ....................................
.......................... 236
3.16. M6ssbauer spectra of [Fe 2 (BXDK)(g237
O2CPhCy)(O2CPhCy)(py)2] (13) ....................................
3.17. M6ssbauer spectrum of [Fe 2 (XDK)(p238
02CPhCy)(O2CPhCy)(Me-Im)2] (15) ....................................
3.18. M6ssbauer spectrum of 13O02 ......................................
.... 239
3.19. Kinetic data for the reaction of [Fe 2 (BXDK)(R-O 2 CtBu)(O 2 Ct-Bu)(py)2] (6) with 02 in THF at -77 C ............................ 240
3.20. Kinetic data for the reaction of [Fe 2(XDK)(O2CPhCy)(O2CPhCy)(py)2] (7) with 02 in THF at -77
C .............................................................................................................
... 241
3.21. Kinetic data for the reaction of [Fe 2 (BXDK)(g02CPhCy)(O2CPhCy)(py)2] (13) with 02 in THF at -77
C .........................................................
242
3.22. Kinetic data for the reaction of [Fe 2 (BXDK)(p.0 2CAr)(O 2CAr)(py) 2] (14) with 02 in THF at -77 C ...................... 243
4.1. Electronic absorption spectrum of 1 in THF at -77 OC
(0.98 mM) and with 1.0 equiv of 2,4-di-t-butylphenol
ad ded .......................................................................................................... 268
Figure 4.2. Electronic absorption spectrum of 2 in CH 2Cl 2 at -77
'C (0.82 mM) and with 1.2 equiv of 2,4-di-tbutylphenol added ......................................................
...................... 269
Figure 4.3. Electronic absorption spectrum of 1 in THF at -77 'C
(0.90 mM) and with 1.2 equiv of phenol added............................270
4.4.
Electronic
absorption spectrum of 1 in THF at -77 "C
Figure
(0.63 mM) and with 1.1 equiv of pentafluorophenol
.................. 271
added.................................................................................
Figure 4.5. Resonance Raman spectra of 1-1602 and 1-1602 + 1.1
.......... 272
equiv of 2,4-di-tert-butylphenol .................................................
Figure 4.6. Resonance Raman spectra of 1-1802) and (B) 1-1802 +
1.1 equiv of 2,4-di-tert-butylphenol.....................................................273
Figure 4.7. Electronic absorption spectrum of 1 in cyclopentane at
-77 'C (0.84 mM) and with 2 equiv of 2,4,6-tri-tertbutylphenol added..................................................................................274
Figure 4.8. Electronic absorption spectrum of 1 in toluene at -77
°C (0.86 mM), and after 1.1 equiv of HO 2CPhCy was
275
added ..........................................................................................................
Figure 4.9. Electronic absorption spectrum of 1 in Et20 at -77 "C
.......
276
(0.98 mM) and after CO 2 addition.................................
Figure 4.10. Electronic absorption spectrum of 2 in CH 2C12 at -77
"C (0.82 mM) in the presence of excess CO 2.............. .. ......... . . .... 277
Figure 4.11. Electronic absorption spectrum of 1 in Et 2 0 at -77 "C
(0.79 mM), and in the presence of 1.1 equiv of
278
Cp 2 *Fe.................................................................................................
Figure 4.12. Electronic absorption spectrum of 1 in THF at -77 "C
(0.79 mM), and after 1.1 equiv of Cp2Co was added..........279
Figure 4.13. A representative GC chromatogram for cyclopentane
.............
280
oxidation reactions with peroxo 1 .....................................
for
THF
Figure 4.14. A representative GC chromatogram
oxidation reactions with peroxo 1......................................281
Figure 4.15. A GC-MS chromatogram for a competitive
deuterium isotope effect measurement for THF
282
oxidation by peroxo 1 ................................................
Figure 4.16. A GC-MS chromatogram for a competitive
deuterium isotope effect measurement for toluene
oxidation by peroxo 1 .................................................
283
Chapter I
Synthesis and Characterization of a Novel Class of Dicopper(I) Bis(carboxylate)Bridged Complexes 1,2
Introduction
The preparation of multinuclear complexes of transition metal ions in low
oxidation states for the reductive activation of small molecules is of fundamental
and practical importance in bioinorganic chemistry. Many metalloenzymes utilize
this strategy to achieve atom transfer reactions which pose a formidable challenge to
the synthetic chemist. For example, soluble methane monooxygenase (sMMO) contains a diiron active site and catalyzes the reaction of dioxygen with methane to produce methanol and water. 3-5 Particulate pMMO carries out the same reaction with a
tricopper, 6-9 or possibly a copper-iron, 10 active site. Dopamine 1-monooxygenase
contains a dicopper active site and catalyzes the 02-promoted hydroxylation of a benzylic CH bond in phenethylamine derivatives.1 1,12 Tyrosinase utilizes a dinuclear
copper active site to catalyze the orthohydroxylation of monophenols and the oxidation of catechol derivatives to orthoquinones. 6 Inspired by these natural successes,
we seek to prepare functional model complexes of some of the forgoing enzymes to
gain a general mechanistic understanding of how two or more metal ions can work
in concert to activate dioxygen reductively and harness its oxidizing equivalents for
oxygen atom transfer reactions to a suitable substrate molecule. The specific reactions of interest are the hydroxylation of aliphatic, aromatic, and olefinic hydrocarbons where the oxygen atom equivalent is derived from 02. Because we are primarily concerned with exploring the basic principles of multimetal-mediated oxidation
reactions, our choice of ancillary ligands is not restricted to mimic the active site
residues in any particular enzyme. The target complexes for examining these reactions are required only to have discrete dinuclear units with sufficient kinetic stability toward metal ion rearrangements to avoid thermodynamically viable and catalytically inactive species along an oxidation reaction pathway.
As an initial approach to this objective we have assembled dimetallic complexes with a class of convergent bis(carboxylate) ligands derived from xylene di-
amine Kemp's triacid. 13-20 Its attributes include: (a) the carboxylate functional group,
which forms a host of bridged dinuclear complexes having the desired 2-5
R
Heq
R
0
R
OH
Hax
Hax
SO
Heq
HO
Hax
O Heq
O
Heq
_
R H 2XDK; R = methyl
N
R
A
o
H 2 PXDK; R = propyl
N
R
H 2 BXDK; R = benzyl
metal-metal distance; 2 1 (b) a pair of preorganized and conformationally rigid carboxylates, which tightly bind two metal ions and resist the formation of higher
metal aggregates; 19 and (c) variable substituents (R) peripheral to the metal binding
sites, which provide more steric protection than simple carboxylate ligands.
The reduced metal ion pairs of particular interest to us for exploring O-atom
transfer chemistry following reductive activation of dioxygen are homo- and het22- 26 and iron 3 , 13 , 2 7 -2 9
erodimetallic combinations of Cu(I) and Fe(II). Copper
oxygenases and hydroxylases have been the subject of an enormous body of
structural and functional modeling literature. We are particularly interested in the
effects of the basic carboxylate ligand environment for stabilizing oxygen
intermediates and for inducing oxo transfer reactivity. A program to investigate the
diiron(II) chemistry of this bis(carboxylate) ligand system for the functional
131 4,30
modeling of sMMO, in particular, is in progress. ,
In the present paper, we report the preparation and characterization of a new
class of dicopper(I) bis(carboxylate) complexes carried out as a prelude to an evaluation of their potential to promote hydrocarbon oxidation. The synthesis of a sterically more demanding derivative of H 2XDK,3 1 H 2BXDK, is described. Both of these
ligands as well as H 2PXDK have been used to prepare complexes with Cu(I). The reactivity of the resulting dicopper(I) XDK species with neutral ancillary ligands has
been explored to elucidate fully the electronic nature of this platform and to map
out its coordination chemistry. Several unprecedented copper(I) carboxylates were
obtained. The dicopper(I) complexes of all three carboxylate ligands have been used
in 02 reactivity studies, affording some stable peroxo intermediates at low temperature. These investigations will be described elsewhere. 32
Experimental Section
General Considerations. The H 2XDK (1) 33 and H 2 PXDK (2) 13 ligands were
prepared according to literature procedures. All reagents were obtained from commercial sources unless otherwise noted. THF, benzene, toluene, pentane, and Et 2 0
were distilled from sodium benzophenone ketyl under nitrogen. Dichloromethane
and chlorobenzene were distilled from CaH2 under nitrogen. Acetonitrile was predistilled from CaH2 and then from P2 0 5 . The NMR solvents CDC13, CD 2C12 , and
C6 D6 were degassed, passed through activated basic alumina, and stored over 3
A
molecular sieves prior to use. All other solvents and reagents are commercially
available and were used as received. All air sensitive manipulations were carried
out either in a nitrogen filled Vacuum Atmospheres drybox or by standard Schlenk
line techniques at room temperature unless otherwise noted.
Physical Measurements. NMR spectra were recorded on Bruker AC-250,
Varian XL-300, or Varian VXR-500 NMR spectrometers. 1H and
13C{ 1H}
NMR chem-
ical shifts are reported versus tetramethylsilane and referenced to the residual solvent peak. 3 1P NMR chemical shifts are reported versus external H 3PO 4 (85%). FTIR
spectra were recorded on a BioRad FTS-135 FTIR spectrometer, and mass spectra
were determined by using a Finnigan 4000 mass spectrometer with 70-eV impact
ionization. UV-vis spectra were recorded on a Cary 1E spectrophotometer.
Conductivity measurements were carried out in CH 2C12 at 296 K with a Fisher
Scientific conductivity bridge model 9-326 with a platinum black electrode.
Elemental analyses were performed by Microlytics, South Deerfield, MA.
Synthesis. Trimethyl-cis,cis-1,3,5-tribenzylcyclohexane-l,3,5-tricarboxylate
(Benzyl Kemp's Triester, 3). To a mechanically stirred solution of lithium
diisopropyl amide (1.5 M in THF, 200 mL, 297 mmol) and toluene (400 mL) at 0 OC
under N 2 was added trimethyl-1,3,5-cyclohexyltricarboxylate (24.0 g, 92.9 mmol) in
toluene (300 mL) dropwise over 1 h. The mixture was allowed to stir an additional
0.5 h, and then benzyl bromide (35.4 mL, 297 mmol) was added via syringe in one
portion. The mixture was warmed to room temperature and then refluxed for 7 h.
After this time the reaction was cooled to room temperature and quenched with
H 20 (200-300 mL). The organic phase was collected and concentrated in vacuo. The
resulting oily residue was taken up in CH 2C12 (200 mL) and extracted with 2 M HCI
(2 X 100 mL) and brine (100 mL). The combined organic extracts were dried with
MgSO4, and the volatile components were removed in vacuo. The resulting orangebrown solid was suspended in dry Et 20 (200-300 mL) and then isolated by filtration
to yield 3 (>95% pure by
1H
NMR) as a light yellow solid (31.9 g, 65%).
Recrystallization from toluene/pentane provided 3 as colorless blocks. 1H NMR (250
MHz, DMSO, 296 K) 8 7.32-7.20 (9H, m), 7.07 (6H, d, J = 6.6 Hz), 3.43 (9H, s), 2.82 (6H,
s), 2.41 (3H, d, J = 14.1 Hz), 1.46 (3H, d, J = 14.1 Hz) ppm; IR (KBr) 3060, 3027, 3000,
2946, 2895, 1738, 1602, 1495, 1451, 1383, 1233, 1206, 1121, 1038, 993, 874, 770, 698, 549 cm1. High resolution MS (FAB) Calcd for C33H 360 6 (M): m/e 528.2512. Found: 528.2505.
Anal. Calcd for C33H360 6: C, 74.98; H, 6.86. Found: C, 75.35; H, 6.85.
cis,cis-1,3,5-Tribenzylcyclohexane-1,3,5-tricarboxylic
acid (Benzyl Kemp's
Triacid, 4). To a stirred solution of 3 (25.3 g, 47.8 mmol) in EtOH/THF (1:1, 500 mL total volume) was added KOH (63.0 g, 955 mmol) in a minimum amount of H 2 0, and
the mixture was refluxed for 6 h. The mixture was concentrated in vacuo to a vis-
cous oily solid. It was redissolved in H20 (300 mL), cooled to 0 oC, and acidified to
pH 1 with concentrated HC1. The resulting yellow precipitate was isolated by filtration, washed with H 20 (300-400 mL), and dried in vacuo at 110 OC for 2 h. The powder was then suspended in dry Et 20 and isolated by filtration to yield 4 (>95% pure
by
1H
NMR) as a white solid (18.4 g, 79%). Recrystallization from ace-
tone/DMSO/Et20 afforded 4 as colorless blocks. 1H NMR (300 MHz, DMSO, 296 K) 8
12.04 (1H, s), 7.29-7.14 (15H, m), 2.86 (6H, s), 2.39 (3H, d, J = 14.7 Hz), 1.47 (3H, d, J =
13.8 Hz) ppm; IR (KBr) 3010, 2615, 1729, 1698, 1603, 1496, 1457, 1291, 1198, 1127, 1031,
915, 767, 699, 553 cm-1 . Anal. Calcd for C34 H 42 0 8 S2 (4.2DMSO): C, 63.53; H, 6.59.
Found: C, 63.44; H, 6.54. The 4.2DMSO stoichiometry was determined by X-ray
crystallography.
cis,cis-1,3,5-Tribenzylcyclohexane-1,3-anhydride-5-acidchloride (Tribenzyl
Kemp's Anhydride Acid Chloride, 5). This compound was prepared from 4 (22.3 g,
45.8 mmol) and excess SOC12 (100 mL) by a procedure analogous to one used for the
synthesis of the parent trimethyl derivative33 to yield 5 (>95% pure by 1H NMR) as a
white solid (22.3 g, 100%). 1H NMR (250 MHz, CDC13 , 296 K) 8 7.40-7.25 (10H, m),
7.10-7.03 (5H, m), 3.21 (2H, d, J = 13.6 Hz), 2.91-2.84 (4H, m), 2.70 (2H, d, J = 14.4 Hz),
1.87 (1H, d, J = 12.9 Hz), 1.45 (2H, d, J = 14.4 Hz), 1.16 (1H, d, J = 13.2 Hz) ppm; IR (KBr)
3062, 3030, 2961, 2928, 1803, 1767, 1604, 1496, 1455, 1445, 1213, 1099, 1057, 1000, 991, 898,
760, 701, 609, 537 cm -1 . High resolution MS (FAB) Calcd for C3 0H 2 70 4C1 (M): m/e
486.1598. Found: 486.1598.
Benzyl Xylene Diamine Kemp's Triacid (H2 BXDK, 6). This compound was
prepared from 5 (22.3 g, 45.8 mmol), 1,3-dimethyl-4,6-diaminobenzene (3.27 g, 24.0
mmol), and 4-dimethylaminopyridine (300 mg, 2.40 mmol) by a procedure analogous to that used to prepare H 2 XDK (1). 33 Recrystallization from MeOH yielded 6
(>95% pure by
1H
NMR) as a white microcrystalline solid (16.6 g, 70%).
Recrystallization from CHCl 3 /pentane provided 6 as colorless blocks which ap-
peared suitable for X-ray crystallography. 1 H NMR (300 MHz, CDC13 , 296 K) 8 7.327.28 (4H, m), 7.21-6.95 (27 H, m), 6.54 (1H, s), 3.40 (4H, d, J = 13.2 Hz), 2.75 (4H, d, J =
13.8 Hz), 2.56 (4H, s), 2.31 (4H, d, J = 13.5 Hz), 2.02 (2H, d, J = 13.0 Hz), 1.18 (6H, s), 1.03
(4H, d, J = 14.1 Hz), 0.89 (2H, d, J = 13.2 Hz) ppm;
13 C{ 1 H}
NMR (125 mHz, CDC13 , 296
K) 8 181.6, 173.7, 136.0, 135.4, 135.0, 133.0, 132.9, 131.2, 130.0, 128.4, 128.0, 127.6, 126.8,
126.2, 50.2, 47.3, 45.0, 44.4, 41.8, 36.9, 16.0 ppm; IR (KBr) 3027, 2955, 2924, 2863, 1795,
1707, 1603, 1495, 1461, 1368, 1326, 1231, 1178, 1031, 934, 744, 700, 585, 517 cm- 1 . High
resolution MS (FAB) Calcd for C 68 H 6 4 N 2 0
8
(M): mle 1036.4663. Found: 1036.4652.
Anal. Calcd for C68 H 64 N 2 0 8 : C, 78.74; H, 6.22; N, 2.70. Found: C, 78.18; H, 6.22; N, 2.67.
This sample and others with the BXDK ligand repeatedly analyzed low for carbon,
perhaps due to its highly unsaturated composition.
T12 (XDK) (7). To a rapidly stirred suspension of 1 (4.00 g, 6.89 mM) in dry THF
(100 mL) under N 2 was added TIOEt (1.0 mL, 14 mM) by syringe. The solution initially clarified and then a white precipitate formed immediately. The mixture was
stirred for 4 h, and the volatile components were removed in vacuo, affording 7 (>
95% pure by 1 H NMR) as a white powder (6.80 g, 100%). 1 H NMR (300 MHz, CDC13 ,
296 K) 8 7.64 (1H, s), 7.08 (1H, s), 2.72 (4H, d, J = 13.0 Hz), 2.08 (2H, d, J = 13.2 Hz), 1.90
(6H, s), 1.44 (2H, d, J = 13.2 Hz), 1.27 (12H, s), 1.16 (6H, s), 1.12 (4H, d, J = 14.1 Hz) ppm;
IR(KBr) 2958, 2909, 2877, 1728, 1686, 1584, 1459, 1354, 1190, 1086, 958, 884, 761, 632 cm- 1 .
High resolution MS (FAB) Calcd for C 3 2 H 38 N 2 0 8 T12 (M): m/e 988.2116. Found
989.2195 (MH+).
T12 (PXDK) (8). This compound was prepared from 2 (8.00 g, 10.7 mmol) and
T1OEt (1.54 mL, 21.4 mmol) by a procedure analogous to that used to prepare 7.
Compound 8 was obtained (>95% pure by 1 H NMR) as a white powder (12.3 g, 100%).
1H
NMR (250 MHz, CD 2 C12 , 296 K) 6 7.38 (1H, s), 7.13 (1H, s), 2.61 (4H, d, J = 13.0 Hz),
2.36 (2H, d, J = 13.0 Hz), 2.10-1.90 (10 H, m), 1.55-1.10 (26 H, m), 1.00-0.80 (18H, m)
ppm;
13 C{1 H}
NMR (75 mHz, CDC13 , 296 K) 8 181.9, 177.0, 134.8, 133.5, 133.2, 128.7,
48.4, 44.3, 43.8, 42.4, 37.7, 25.8, 18.2, 17.9, 17.3, 14.8 ppm; IR (KBr) 2959, 2871, 1734, 1685,
1558, 1499, 1436, 1391, 1361, 1310, 1246, 1185, 1163, 1106, 1035, 930, 861, 760, 629 cm- 1.
High resolution MS (FAB) Calcd for C4 4H 6 2N 20 8T12 (M): m/e 1156.3994. Found:
1157.4065 (MH+).
T12 (BXDK) (9). This compound was prepared from crude 6 (3.00 g, 2.89 mmol)
and TlOEt (418 gL, 5.78 mmol) by a procedure analogous to that used to prepare 7, affording 9 (>95% pure by 1H NMR) as a tan powder. Recrystallization from
CH 2 Cl 2 /Et 20 gave 9 as a white microcrystalline solid (3.38 g, 81%). 1H NMR (300
MHz, C6 D 6 , 296 K) 8 7.88 (1H, s), 7.30-7.23 (4H, m), 7.21-6.98 (26H, m), 6.51 (1H, s), 3.48
(4H, s, J = 12.9 Hz), 2.97 (4H, d, J = 12.9 Hz), 2.82 (4H, s), 2.49 (4H, d, J = 12.9 Hz), 2.07
(4H, d, J = 12.9 Hz), 1.18 (4H, d, J = 12.9 Hz), 1.02 (2H, d, J = 13.2 Hz), 0.96 (6H, s) ppm;
13 C{ 1H} NMR (75 mHz, CDC13, 296 K) 8 180.4, 176.2, 138.6, 136.9, 135.6, 133.5, 133.4,
131.8, 131.3, 128.8, 128.6, 128.4, 127.2, 127.1, 51.0, 50.5, 45.9, 45.4, 43.5, 37.9, 16.6 ppm; IR
(KBr) 3083, 3027, 2916, 1731, 1681, 1559, 1453, 1357, 1187, 1031, 937, 865, 741, 700, 602,
508 cm -1 . High resolution MS (FAB) Calcd for C6 8H 6 2N 20 8 T12 (M): m/e 1444.3994.
Found: 1445.4061.
[Cu 2 (XDK)(MeCN)] (10). To a stirred solution of 7 (3.67 g, 3.72 mmol) in
CH 2Cl 2 /MeCN (3:1, 300 mL) under N 2 was added solid CuBr(Me2S) (2.32 g, 11.1
mmol), and the mixture was rapidly stirred for 3 h. The salts were then removed by
filtration through celite. The filtrate was treated with three more equiv of
CuBr(Me2S) and stirred for 1 h. The solvent was removed in vacuo, and the solid
residue was extracted with CH 2C12 (200 mL) followed by filtration through celite. The
precipitate was extracted with additional CH 2C12 (100 mL) and filtered through celite.
The combined filtrates were concentrated in vacuo to yield a solid residue. It was
suspended in Et 20, and the precipitate was recovered by filtration to yield 10 (> 95%
pure by 1H NMR) as a white solid (2.50 g, 90%). The crude powder was used without
further purification for subsequent reactions. Recrystallization from MeCN/CH 2Cl 2-
/Et20 afforded 10 as colorless blocks which appeared suitable for X-ray
crystallography. 1H NMR (300 MHz, C6D6, 296 K) 8 8.47 (1H, s), 6.70 (1H, s), 2.83 (4H,
d, J = 13.1 Hz), 2.05 (3H, br s), 1.77 (6H, s), 1.71 (2H, d, J = 15.0 Hz), 1.20 (12H, s), 0.82
(2H, d, J= 13.1 Hz), 0.75 (4H, d, J = 13.5Hz), 0.63 (6H, s) ppm;
13C{ 1H}
NMR (75 mHz,
CD 2C12, 296 K) 8 186.4, 177.1, 135.7, 134.9, 133.7, 128.5, 117.6, 45.7, 45.2, 43.4, 41.7, 31.5,
26.5, 17.5, 2.6 ppm; IR(KBr) 2963, 2921, 1738, 1704, 1568, 1463, 1403, 1357, 1176, 1086,
957, 891, 849, 759, 734, 622
cm -1. Anal. Calcd for C34H4 1N 308Cu 2 : C, 54.68; H, 5.53; N, 5.63. Found: C, 54.39; H,
5.58; N, 5.94.
[Cu 2 (PXDK)(MeCN)] (11). This compound was prepared from 8 (500 mg, 0.433
mmol) and CuBr(Me2S) (241 mg, 130 mmol) by a procedure analogous to that used
to synthesize 10, affording 11 (>95% pure by 1H NMR) as a white powder (360 mg,
91%). The crude powder was used without further purification for subsequent reactions. Recrystallization from CH 2 Cl 2 /MeCN/Et 20 gave 11 as colorless needles. 1H
NMR (500 MHz, CD 2Cl 2, 296 K) 5 8.23 (1H, s), 7.17 (1H, s), 2.69 (4H, d, J = 13.5 Hz), 2.39
(2H, d, J = 12.5Hz), 2.00-1.92 (13H, m), 1.42-1.18 (26H, m), 0.92 (12H, t, J = 7.0 Hz), 0.84
(6H, t, J = 7.2 Hz) ppm;
13 C{1H}
NMR (75 mHz, CDC13, 296 K) 8 185.4, 176.3, 135.5,
134.9, 133.7, 129.1, 117.8, 48.1, 46.9, 44.7, 42.6, 38.2, 18.0, 17.6, 15.7, 15.0, 14.8, 2.5 ppm (18
of the expected 19 peaks were observed); IR(KBr) 2959, 2872, 1734, 1695, 1566, 1458,
1359, 1247, 1182, 1035, 924, 863, 759, 583 cm-1. Anal. Calcd for C44H 62N 208Cu2 C12 (11
minus 1MeCN): C, 60.46; H, 7.15; N, 3.20. Found: C, 60.01; H, 7.32; N, 3.22. This sample was heated at 90 OC for 12 h to remove any residual CH 2C12. The MeCN ligand
was removed in the process.
ICu 2 (BXDK)(MeCN)] (12). This compound was synthesized from 9 (1.00 g,
0.692 mmol) and CuBr(Me2S) (435 mg, 2.08 mmol) by a procedure analogous to that
used to prepare 10, to yield 12 (> 95% pure by 1H NMR) as a white solid. The crude
powder was used without further purification for subsequent reactions.
Recrystallization from MeCN/CH 2Cl 2 /Et 20 afforded 12 as colorless thin plates (600
mg, 72%). 1H NMR (300 MHz, C6D 6, 296 K) 8 8.22 (1H, s), 7.25-6.95 (30 H, m), 6.54 (1H,
s), 3.51 (4H, d, J = 13.2 Hz), 2.85 (4H, d, J = 13.2 Hz), 2.59 (4H, s), 2.41 (4H, d, J = 12.9 Hz),
2.04 (2H, d, J = 12.6 Hz), 1.90 (3H, br s), 1.10 (4H, d, J = 14.1 Hz), 0.94 (2H, d, J = 13.2 Hz),
0.82 (6H, s) ppm;
1 3C{1H}
NMR (75 mHz, CDC13 , 296 K) 8 182.5, 175.3, 137.6, 136.7,
135.9, 134.3, 134.0, 132.0, 130.9, 128.5, 128.4, 128.3, 127.4, 127.1, 117.5, 50.1, 49.0, 46.2, 45.2,
43.6, 38.1, 15.8, 2.6 ppm; IR(KBr) 3084, 3061, 3028, 2926, 2860, 2251, 1732, 1700, 1565,
1494, 1413, 1359, 1231, 1178, 1031, 928, 844, 749, 698 cm- 1 . Anal. Calcd for
C68H6 2N 208Cu2 (12 minus 1MeCN): C, 70.27; H, 5.38; N, 2.41. Found: C, 67.67; H, 5.30;
N, 2.68. This sample was heated at 90 oC for 12 h to remove any residual CH 2Cl 2 . The
MeCN ligand was removed in the process.
[Cu 2 (XDK)(PPh 3)2 ] (13). To a stirred suspension of 10 (50 mg, 0.067 mmol) in
THF (2 mL) was added PPh 3 (35 mg, 0.13 mmol) in THF (1 mL). The mixture clarified immediately and after 0.5 h the solvent was removed in vacuo. The solid
residue was recrystallized from chlorobenzene/Et20 to yield 13 as colorless blocks
which appeared suitable for X-ray crystallography (45 mg, 55 %). 1H NMR (300 MHz,
C6D 6, 296 K) 8 8.05 (1H, s), 7.50-7.43 (10 H, m), 7.04-7.00 (20H, m), 6.80 (1H, s), 2.98 (4H,
d, J = 13.2 Hz), 1.89 (6H, s), 1.79 (2H, d, J = 12.5 Hz), 1.22 (12 H, s), 0.90 (2H, d, J = 13.2
Hz), 0.92-0.78 (10H, m) ppm; 13 C{lH} NMR (75 mHz, CD 2C12 , 296 K) 8 182.5, 176.8,
135.2, 135.1, 134.5 (d, J cp= 15.8 Hz), 133.6, 133.1 (d, J cp= 15.1 Hz), 130.4, 129.1 (d, J Cp=
9.3 Hz), 128.8, 45.6, 45.4, 43.5, 41.3, 32.8, 26.5, 17.5 ppm; 31p NMR (121 mHz, CD 2C12,
296 K) 8 5.43 (br s, Av1 / 2 = 45.4 Hz) ppm; IR(KBr) 3070, 2961, 2926, 1733, 1695, 1571,
1461, 1435, 1400, 1359, 1195, 1097, 958, 851, 745, 694 cm
-1 .
Anal. Calcd for
C6 8H68N 208P2Cu 2: C, 66.38; H, 5.57; N, 2.28. Found: C, 66.07; H, 5.79; N, 2.15.
[Cu 2 (XDK)(2,6-Me 2 PhNC) 3] (14a) and [Cu 2 (XDK) (-2,6-Me2PhNC)(2,6Me 2 PhNC) 2] (14b). This compound was prepared from 10 (100 mg, 0.13 mmol) and
2,6-dimethylphenyl isocyanide (54 mg, 0.40 mmol) by a procedure analogous to that
used to make 13. Recrystallization from PhC1/Et 20 (vapor diffusion) afforded blocks
of colorless 14a and yellow 14b in distinct crystal fields, both of which appeared suitable for X-ray crystallography (96 mg, 65%). 1H NMR (300 MHz, C6 D6 , 296 K) 8 8.05
(1H, s), 7.50-7.43 (10H, m), 7.04-7.00 (20H, m), 6.80 (1H, s), 2.98 (4H, d, J = 13.2 Hz), 1.89
(6H, s), 1.79 (2H, d, J = 12.5 Hz), 1.22 (12H, s), 0.90 (2H, d, J = 13.2 Hz), 0.92-0.78 (10H,
m) ppm;
13 C{ 1H}
NMR (75 mHz, CD 2C12, 296 K) 8 182.9, 176.8, 135.7, 135.1, 134.6,
132.0, 130.2, 129.9, 129.0, 128.4, 127.1, 45.9, 45.8, 43.3, 41.3, 33.0, 26.7, 19.0, 17.6 ppm; IR
(KBr) 2957, 2926, 2877, 2134, 1736, 1701, 1592, 1462, 1356, 1197, 1085, 960, 887, 793, 749,
720, 635 cm- 1. Anal. Calcd for C59 H65 N50 8Cu 2: C, 64.46; H, 5.96; N, 6.37. Found: C,
64.54; H, 5.94; N, 6.04.
[Cu 2 (XDK)(NB) 2] (15). This compound was prepared from 10 (80 mg, 0.11
mmol) and excess norbornene (650 mg, 6.9 mmol) by a procedure analogous to that
used to make 13. Recrystallization from NB/CH 2C12 /Et 2 0 provided 15 as colorless
blocks (69 mg, 72%). 1H NMR (300 MHz, CD 2C12, 296 K) 8 7.24 (1H, s), 7.10 (1H, s), 5.41
(4H, s), 2.85-2.77 (8H, m), 2.06 (2H, d, J = 13.2 MHz), 2.83 (6H, s), 1.58-1.41 (8H, m), 1.321.25 (18H, m), 1.20 (4H, d, J = 13.8 Hz), 1.01 (2H, d, J = 8.7 Hz), 0.80 (4H, dd, J = 7.5, 2.4
Hz) ppm; 13C{1H) NMR (75 MHz, CD 2C12, 296 K) 8 186.4, 176.8, 135.5, 134.8, 133.6,
127.7, 120.2, 47.4, 45.4, 45.1, 43.7, 42.7, 41.6, 32.4, 26.3, 24.8, 17.5 ppm; IR (KBr) 2957,
2926, 2877, 2134, 1736, 1701, 1592, 1462, 1356, 1197, 1085, 960, 887, 793, 749, 720, 635
cm -1 . Prolonged exposure of powdered 15 to high vacuum resulted in removal of 1
equiv of NB, as judged by
1H
NMR and elemental analysis.
1H
NMR for
[Cu 2 (XDK)(NB)]: (300 MHz, CD 2C12 , 296 K): 8 7.58 (1H, s), 7.13 (1H, s), 5.27 (2H, s), 2.852.74 (6H, m), 2.08 (2H, d, J = 13.5 Hz), 1.89 (6H, s), 1.59-1.51 (4H, m), 1.47 (2H, d, J = 13.2
Hz), 1.28 (12H, s), 1.25 (6H, s), 1.17 (4H, d, J = 12.6 Hz), 1.00 (2H, d, J = 13.1 Hz), 0.91
(2H, dd, J = 7.4, 2.4 Hz); IR (KBr) 2966, 2928, 1733, 1696, 1592, 1460, 1407, 1356, 1335,
1223, 1136, 957, 851, 760, 684, 638 cm - 1. Anal. Calcd for C59H 6 5N 508Cu 2 (15 minus
1NB): C, 64.46; H, 5.96; N, 6.37. Found: C, 64.54; H, 5.94; N, 6.04.
Cu 2 (XDK) (16). This compound was prepared from 10 (290 mg, 0.38 mmol)
and excess cyclohexene (5.0 ml, 49 mmol) by a procedure analogous to that used to
prepare 15. Upon removal of the volatile components in vacuo, all the cyclohexene
was driven off to afford 16 as a white solid. Recrystallization from CH2C12/pentane
provided 16 as colorless needles (220 mg, 81%). 1H NMR (300 MHz, CD 2C12, 295 K) 8
8.08 (1H, s), 7.14 (1H, s), 2.77 (4H, d, J = 13.2 Hz), 2.09 (2H, d, J = 13.2 Hz), 1.90 (6H, s),
1.46 (2H, d, J = 13.2 Hz), 1.27 (12H, s), 1.23-1.15 (10H, m) ppm;
13C{1 H}
NMR (75 MHz,
CD 2C12, 296 K) 8 187.7, 177.1, 135.8, 134.8, 134.1, 130.4, 45.7, 45.2, 43.6, 41.7, 31.4, 26.4,
17.5 ppm; IR (KBr) 2965, 2924, 1734, 1697, 1559, 1501, 1411, 1341, 1228, 1179, 1087, 956,
848, 761, 700, 623 cm-1 . Anal. Calcd for C32 H 3 8 N 2 08Cu 2 : C, 54.46; H, 5.43; N, 3.97.
Found: C, 54.67; H, 5.36; N, 3.75.
[Cu 2 (XDK)(tmeda)] (17). This compound was prepared by addition of tmeda
(23 gL, 0.15 mmol) to 10 (94 mg, 0.13 mmol) in THF (1 mL), followed by recrystallization from THF/pentane at -30 OC, to afford 17 as colorless blocks (81 mg, 78 %). 1H
NMR (295 K, 300 MHz, C6 D6 ) 8 8.45 (1H, s), 6.69 (1H, s), 2.94 (4H, d, J = 13.1 Hz), 2.10
(12 H, s), 1.86 (4H, s), 1.85-1.78 (8H, m), 1.26 (12H, s), 1.05 (6H, s), 0.92 (2H, d, J = 13.1
Hz), 0.84 (4H, d, J = 13.8 Hz);
13C{ 1H}
NMR (75 MHz, CD 2 Cl 2 , 296 K) 8 184.2, 176.8,
135.2, 133.5, 129.2, 58.5, 47.3, 45.9, 45.5, 42.9, 41.6, 31.9, 26.6, 17.5 ppm (14 of the expected 15 peaks were observed); IR(KBr) 2984, 2930, 2882, 1735, 1695, 1561, 1461, 1355,
1189, 1086, 957, 850, 697 cm - 1 . Anal. Calcd for C3 8 H 54 N 4 08Cu 2 : C, 55.53; H, 6.62; N,
6.82. Found: C, 55.39; H, 6.80; N, 6.81.
[Cu 2 (PXDK)(tmeda)] (18). This compound was prepared from 11 (57 mg, 0.062
mmol) and tmeda (19 gL, 0.50 mmol) by a procedure analogous to that used to obtain 17. Recrystallization from THF/pentane provided 18 as colorless needles (39 mg,
72%). 1H NMR (250 MHz, CD 2C12, 295 K) 8 8.02 (1H, s), 7.10 (1H, s), 2.73 (4H, d, J = 12.9
Hz), 2.36 (4H, s), 2.23 (12H, s), 2.00-1.85 (8H, m), 1.50-1.12 (30H, m), 0.91 (12H, d, J = 6.6
Hz), 0.77 (6H, t, J = 6.7 Hz) ppm;
13C{ 1H}
NMR (75 MHz, CD 2C12, 296 K) 8 138.2, 176.0,
135.2, 135.1, 133.4, 129.9, 58.6, 48.2, 47.2, 46.4, 44.5, 42.8, 38.5, 18.0, 17.6, 15.1, 14.6 ppm
(17 of the expected 19 peaks were observed); IR(KBr) 2958, 2871, 2780, 1733, 1691, 1579,
1459, 1361, 1192, 923, 758, 582 cm- 1. Anal. Calcd for C5oH78N 4 08Cu 2: C, 60.64; H, 7.94;
N, 5.66. Found: C, 59.99; H, 8.32; N, 6.56.
[Cu 2 (BXDK)(tmeda)] (19). This compound was prepared from 12 (200 mg, 0.17
mmol) and tmeda (75 gL, 0.50 mmol) by a procedure analogous to that used to synthesize 17. Recrystallization from THF/pentane provided 19 as colorless needles (138
mg, 65%). 1H NMR (300 MHz, CD 2Cl 2, 295 K) 8 7.91 (1H, s), 7.38-7.22 (6H, m), 7.20-7.05
(24H, m), 6.66 (1H, s), 3.30 (4H, d, J = 12.9 Hz), 2.81 (4H, s), 2.76 (4H, d, J = 13.2 Hz),
2.55-2.45 (8H, m), 2.40 (12 H, s), 1.99 (2H, d, J = 12.6 Hz), 1.36 (4H, d, J = 13.2 Hz), 1.00
(2H, d, J = 12.9 Hz), 0.62 (6H, s) ppm;
13 C{ 1H}
NMR (75 MHz, CD 2C12 , 296 K) 8 183.9,
175.0, 137.0, 136.9, 135.2, 134.5, 133.9, 132.0, 131.9, 129.4, 128.5, 128.2, 127.2, 126.9, 58.5,
48.8, 48.1, 47.7, 45.7, 45.3, 41.5, 38.0, 16.0 ppm; IR(KBr) 3027, 2920, 2828, 1733, 1694, 1577,
1495, 1361, 1184, 1032, 932, 759, 701, 596 cm -1. Anal. Calcd for C7 4 H 78N 4 08Cu 2: C,
69.52; H, 6.15; N, 4.38. Found: C, 68.72; H, 6.45; N, 4.42.
[Cu(4,4'-Me 2bpy) 2][Cu(XDK)] (20). To a stirred solution of 10 (250 mg, 0.355
mmol) in CH 2 Cl 2 (5 mL) was added 4,4'-dimethyl-2,2'-dipyridine (125 mg, 0.670
mmol). The solution immediately turned dark red, and after 0.5 h the volatile components were removed in vacuo. The dried residue was suspended in pentane (10
mL), and the precipitate was recovered by filtration. Recrystallization from
THF/CH2Cl 2 /pentane provided 20 as a dark red-brown microcyrstalline solid (345
mg, 96%). 1H NMR (250 MHz, CD 2C12, 296 K) 8 8.43 (4H, d, J = 5:1 Hz), 8.02 (4H, s),
7.98 (1H, s), 7.33 (4H, d, J = 5.1 Hz), 7.06 (1H, s), 2.71 (4H, d, J = 13.2 Hz), 2.51 (12 H, s),
2.02 (2H, d, J = 12.8 Hz), 1.81 (6H, s), 1.37 (2H, d, J = 13.0 Hz), 1.21 (12H, s), 1.12-0.90
(10H, m);
13 C{ 1H}
NMR (75 MHz, CD 2C12, 296 K) 8 181.6, 176.9, 152.7, 150.2, 149.0,
135.1, 134.9, 132.5, 130.0, 127.5, 122.8, 46.2, 45.9, 42.5, 41.6, 31.6, 26.8, 21.9, 17.7 ppm;
IR(KBr) 2958, 2926, 1734, 1696, 1611, 1460, 1345, 1226, 1193, 1086, 956, 823, 886, 626, 517
cm - 1. UV-vis (CH 2 C12) (Xmax, nm (E, M- 1 cm-1)): 329 (sh, 2800), 397 (2200), 529 (sh,
630). Anal. Calcd for C5 6 H 62 N 6 08Cu 2 : C, 62.61; H, 5.82; N, 7.82. Found: C, 62.30; H,
5.58; N, 7.69.
(Et4 N)[Cu(PXDK)] (21). To a stirred solution of 11 (1.50 g, 1.64 mmol) in
CH 2C12 (25 mL) was added Et 4 N(CN) (272 mg, 1.64 mmol) in CH 2C12 (5 ml). The mixture was rapidly stirred for 0.5 h and then filtered through celite. The colorless filtrate was dried to yield pure 21 (>95% by 1H NMR) as a white powder (1.42 g, 92 %)
Recrystallization from MeCN/THF/Et 20 afforded 21 as colorless blocks. 1H NMR
(250 MHz, CD 2Cl 2, 296 K) 8 7.99 (1H, s), 7.06 (1H, s), 3.26 (8H, m), 2.66 (4H, d, J = 13.0
Hz), 2.32 (2H, d, J = 12.9 Hz), 2.02-1.70 (10H, m), 1.50-1.00 (38 H, m), 0.93-0.70 (18H, m);
13C{ 1H}
NMR (75 MHz, CD 2C12, 296 K) 6 180.4, 176.6, 135.3, 135.0, 132.4, 130.7, 51.8,
48.2, 46.0, 45.1, 44.7, 43.1, 38.6, 19.4, 18.3, 18.0, 17.7, 15.1, 7.8 ppm; IR(KBr) 2933, 2872,
1731, 1700, 1626, 1498, 1458, 1392, 1346, 1257, 1172, 1107, 1003, 924, 860, 826, 782, 759,
734, 539 cm-1 . Anal. Calcd for C52H 84 N 308Cu: C, 66.39; H, 8.79; N, 4.47. Found: C,
66.32; H, 9.02; N, 4.53.
[CuLi(XDK)(THF) 2] (22). Method A: To a stirred solution of 10 (50 mg, 0.067
mmol) and 12-crown-4 (43 mL, 0.27 mmol) in THF (3 mL) was added PhLi (37 mL,
1.8 M in cyclohexane/Et20). The resulting brown mixture was stirred for 2 h, and
then the volatile components were removed in vacuo. The residue was recrystallized from THF/pentane to yield a dark brown precipitate and large colorless blocks.
Crystals of 22 separated from the dark residue in Paratone-N (Exxon) and were suitable for X-ray crystallography, but a large scale purification for spectroscopic and
elemental analysis was unsuccessful by this method.
Method B: To a stirred solution of 10 (100 mg, 0.13 mmol) in THF (5 mL) was
added LiCN (0.5 M in DMF, 268 gl, 0.13 mmol) via syringe in one portion. An offwhite precipitate formed immediately, and after 5 min the mixture was filtered
through celite. The volatile components were removed from the filtrate in vacuo.
The resulting tan solid was washed with pentane (5-10 ml) to remove residual DMF.
The dried residue was redissolved in CH 2C12 (0.5 ml) and filtered through celite to
remove a fine white precipitate. An equal volume of THF was added, and slow diffusion of pentane into this solution provided 22 as large colorless blocks. When
crystalline 22 was isolated from the mother liquor, followed by drying at atmospheric pressure under N 2, one of the THF molecules was lost as judged by 1H NMR
and elemental analysis (75 mg, 78%). 1H NMR for [CuLi(XDK)(THF)] (300 MHz,
CD 2C12, 296 K) 8 7.64 (1H, s), 7.14 (1H, s), 3.69 (4H, t, J = 6.3 Hz), 2.72 (4H, d, J = 13.2
Hz), 2.08 (2H, d, J = 13.2 Hz), 1.91 (6H, s), 1.87-1.80 (4H, m), 1.45 (2H, d, J = 12.9 Hz),
1.34-1.05 (22H, m); 13C{ 1H} NMR (75 MHz, CD 2C12, 296 K) 8 185.1, 177.5, 135.6, 134.7,
133.2, 128.2, 45.7, 45.2, 43.1, 41.7, 32.3, 31.7, 26.5, 26.1, 17.6 ppm; IR(KBr) 2959, 2868,
1736, 1702, 1402, 1376, 1352, 1227, 1184, 1048, 956, 889, 760, 624 cm- 1. Anal. Calcd for
C36H 46N 20 9CuLi (22 minus 1THF): C, 59.95; H, 6.43; N, 3.88. Found: C, 59.64; H, 7.10;
N, 3.43.
Collection and Reduction of X-ray Data
All crystals were mounted on the tips of quartz fibers with Paratone-N
(Exxon), cooled to low temperature (- -85 °C), and placed on Siemens CCD X-ray
diffraction system controlled by a Pentium-based PC running the SMART software
package. 34 The general procedures for data collection and reduction follow those reported previously.35 All structures were solved by use of the direct methods programs SIR-9236 or XS, part of the TEXSAN 3 7 and SHELXTL38 program packages, respectively. Structure refinements were carried out with XL, part of the SHELXTL
program package. 38 All remaining non-hydrogen atoms were located and their positions refined by a series of least-squares cycles and Fourier syntheses. Enantiomorph
checks were carried out on 17 and 21 by using the Flack parameter refinement3 9 in
the XL program. Selection of the correct enantiomer for complex 17 was determined
to be unreliable, so it was refined as a racemic twin, resulting in lower R and wR 2
values than were obtained when refining with either of the two enantiomers.
Selection of the correct enantiomer for 21 was unambiguous. All hydrogen atoms
for 6, 10, and 21 were located from difference Fourier maps and refined isotropically.
For 15, the four olefinic hydrogen atoms of the coordinated norbornene molecules
were located from difference maps and refined isotropically. The remaining hydrogen atoms of 15, and all the hydrogen atoms for 13, 14a, 14b, 16, 17, and 22, were assigned idealized positions and given a thermal parameter 1.2 times the thermal parameter of the carbon atom to which each was attached. Empirical absorption corrections were calculated and applied for each structure using SADABS, part of the
SHELXTL program package.38
The structures of 14a, 14b, and 16 contain a disordered chlorobenzene
molecule. The chlorine atom in each case is disordered across an inversion center
positioned on the centroid of the phenyl ring. Each chlorine atom was refined with
a site occupancy of 0.5. The other chlorobenzene in 16 contains two carbon atoms
with large thermal parameters. The structure of 17 contains two disordered THF
molecules in which the oxygen atoms could not be determined reliably, so both
were refined at partial occupancy as cyclopentane molecules. The structure of 21 contains a lattice THF molecule disordered over two positions. It was refined as a cyclopentane molecule with two of the carbon atoms at full occupancy, and the occupancy of the other three carbon atoms was distributed over two positions and refined. One of the propyl groups of 21 is disordered. The carbon atom attached to the
cyclcohexyl ring was refined at full occupancy, and the occupancy of the other two
carbon atoms was distributed over two positions and refined.
Important crystallographic information for each complex including refinement residuals is given in Table 1.1, along with core distances and angles in Table
1.2. Final positional and equivalent isotropic thermal parameters are provided in
Tables 1.3-1.12.
Results and Discussion
At the inception of this research, very few well characterized copper(I) carboxylate complexes had been described. The most notable work came from Floriani's
lab, which reported the synthesis of carbon monoxide, 40 isonitrile, 41 and alkyne 42
complexes incorporating Cu(I) benzoate. Copper(I) carboxylate complexes without iacceptor ligands, except for oligomeric homoleptic complexes, are rare owing to disproportionation to Cu metal and Cu(II) products. In addition, accounts of the reactivity toward dioxygen of any well defined Cu(I) carboxylate derivatives were nonexistent. Our initial goals were therefore to develop a facile synthesis of a discrete dicopper(I) XDK complex and ascertain its kinetic stability, and to understand the
chemical properties of this bis(carboxylate)-bridged "platform" by fully elucidating its
coordination chemistry with a range of ancillary ligands, ranging from x-acceptor to
sigma-only donors. From these studies has emerged a detailed picture of the electronic nature of the dicopper(I) XDK platform and a host of complexes for 02 reactivity studies.
Ligand Synthesis. Exposure of most dicopper(I) and diiron(II) complexes of
XDK and PXDK to dioxygen at low temperature produces transiently stable intermediates at best. 1 3,43 A possible decomposition pathway in these reactions is the intermolecular reaction between an 02-derived intermediate and one or more {M2 (XDK)}
units.27,28 A more sterically demanding XDK derivative might block this pathway by
impeding access to the intermediate or transition state. This strategy presumes that
the decomposition pathway does not involve complete dissociation of the metal 02derived species from XDK, which may occur in some cases. Nevertheless it represents a reasonable starting point, and we were therefore interested to prepare a sterically more hindered XDK analog.
Derivatization of Kemp's triacid has been achieved by alkylation of trimethyl
1,3,5-cyclohexyltricarboxylate carboxylate with benzyl chloromethyl ether 44 and allyl
bromide, 45 both potent electrophiles. A more sterically demanding and robust substituent than the benzyloxy group was sought which would place a bulky group
closer to the metal binding sites and resist oxidative cleavage. Both neopentyl and
benzyl functionalities fulfill these requirements, but efforts to alkylate with
neopentyl iodide failed owing to its modest electrophilicity. Reaction of trilithio
trimethyl-1,3,5-cyclohexyltricarboxylate with three equivalents of benzyl bromide
under relatively forcing conditions proceeded in good yield, however, affording
multigram quantities of trimethyl-cis,cis-1,3,5-tribenzylcyclohexane-1,3,5-tricarboxylate (benzyl Kemp's triester, 3, Scheme 1.1). Deprotection of 3 in refluxing KOH followed by acidification with HC1 provided cis,cis-1,3,5-tribenzylcyclohexane-1,3,5-tricarboxylic acid (benzyl Kemp's triacid, 4). Under identical conditions but in the absence of THF, only intractable decomposition products were obtained. The tripotassium salt of 4 precipitates out of solution when a 1:1 EtOH/THF solvent mixture is
used, and this property may protect it from further degradation. The final ether
wash also proved crucial for obtaining pure product, for it removed significant
quantities of partially deprotected 3 and other decomposition products. The triacid is
soluble in neat DMSO or DMSO solvent mixtures. Synthesis of cis,cis-1,3,5-tribenzylcyclohexane-1,3-anhydride-5-acid chloride (tribenzyl Kemp's anhydride acid chloride, 5) proceeded by standard procedures33 in quantitative yield.
Condensation of 5 with 0.5 equivalents of 1,3-dimethyl-4,6-diaminobenzene
followed by recrystallization from MeOH provided benzyl xylene diamine Kemp's
triacid (H2 BXDK, 6) in moderate yield and high purity as judged by the 1 H NMR
spectrum of the bulk product. This spectrum also revealed that the benzyl Kemp's
cyclohexyl fragments were in equivalent magnetic environments, supporting the
assignment of C2v symmetry for the product and confirming that the desired Ushaped isomer had been obtained. An X-ray structural determination of 6 confirmed
this assignment (Figure 1.1). The space filling representation reveals that the
peripheral benzyl groups shroud the bis(carboxylate) oxygen plane and the metal
binding sites from above, although rotation toward the outside of the molecule in
solution appears facile. This flexibility would preclude steric protection from the
sides of a BXDK complex. Nevertheless the benzyl groups are still forced to point up
owing to the geometric constraints of the quaternary cyclohexyl carbon atoms and
this property should provide added steric protection at the carboxylate binding sites
compared to XDK and PXDK.
Preparation and Reactivity of Dicopper(I) Bis(carboxylate)-Bridged Complexes:
Synthesis of [TI 2L], L = XDK (7), PXDK (8), and BXDK (9); and ICu 2L(MeCN)], L = XDK
(10), PXDK (11), and BXDK (12). Convenient, high-yield procedures were desired for
the bis(carboxylate) dicopper(I) starting materials. Other Cu(I) carboxylates have been
prepared from their TI(I) salts and a copper halide,4 6 so this approach was adopted
(eq 1). Treatment of 1, 2, or 6 with 2 equiv of TIOEt afforded 7-9, respectively, as
THF, rt, N 2
-2EtOH
[T12(XDK)] (7), [T12(PXDK)] (8),
or [T12 (BXDK)] (9)
L = XDK, PXDK, BXDK
white powders in quantitative yields. The 1H NMR spectra of each dithallium(I)
complex showed one set of cleanly shifted resonances and the disappearance of the
broad singlet due to the carboxylic acid protons. Complex 7 is only slightly soluble in
THF and CH 2C12, whereas 8 and 9 are readily soluble.
Treatment of 7,8 or 9 with excess CuBr(DMS) in CH 2C12 /MeCN provided 1012, respectively, as crude off-white powders in 90% yield (eq 2). The 1 H NMR
excess CuBr(DMS)
[Tl2 L]
L = XDK, PXDK, BXDK CH 2 /MeCN
Lrt,N
=XDKPXDK,
BXDK
2
-2 T1Br
ICu 2(XDK)(MeCN)] (10),
[Cu 2(PXDK)(MeCN)] (11),
or [Cu 2(BXDK)(MeCN)] (12)
(2)
spectrum of each product exhibited a single shifted set of dicarboxylate and MeCN
ligand resonances in a 1:1 ratio. A xylene spacer aromatic proton experiences a significant downfield shift, presumably the one ortho to both imide nitrogen atoms,
which is in close proximity to the metal-binding sites. Recrystallization from
CH 2C12/MeCN/Et 20 afforded colorless blocks or needles. Spectroscopic and analytical data confirm the purity of each complex. Complexes 10-12 are all non-electrolytes
in CH 2 Cl 2 solution, supporting that the metal ions are strongly coordinated by the
carboxylate groups in solution. An X-ray structural determination of 10 confirmed
that both Tl ions were displaced in eq 2 to form a dinuclear copper(I) carboxylatebridged complex. As illustrated in Figure 1.2, one copper atom is ligated by an
acetonitrile and two carboxylate oxygen atoms in a trigonal planar geometry, and the
other is coordinated in a nearly linear, two-coordinate fashion to the other two
carboxylate oxygen atoms. A linear two-coordinate geometry is not uncommon for
Cu(I), 47 which appears to have the ideal ionic radius to be "skewered" by the two
rigidly positioned XDK oxygen atoms. The relatively short Cu...Cu distance of 2.6287
(5)
A
signifies weak metal-metal bonding, a formulation which is supported by
molecular orbital calculations on a tetrameric Cu(I) trimethylsilyl complex with
similar copper-copper distances.48
Reactivity of the Dicopper(I) Acetonitrile Complexes. The reactivity of 10-12
with a spectrum of reagents, weak sigma donors (n-acceptors), basic neutral sigma
donors, and anionic donors was investigated and the results are summarized in
Scheme 1.2. ORTEP diagrams of the structurally characterized products are shown in
Figures 1.3 and 1.4, and selected bond distances and angles are reported in Table 1.2.
The coordination chemistry proved to be essentially identical for all three diacids, so
only that for XDK will be described in detail.
Neutral Donor Adducts: Preparation of [Cu 2(XDK)(PPh3 )2] (13), [Cu 2 (XDK)(2,6Me 2 PhNC)3 ] (14a), [Cu 2(XDK) (p-2,6-Me 2PhNC) (2,6-Me 2PhNC) 2] (14b), [Cu 2 (XDK)-
(NB) 2] (15), ICu 2 (XDK)] (16), [Cu 2 (XDK)(tmeda)] (17), [Cu 2 (PXDK)(tmeda)] (18),
[Cu 2 (BXDK)(tmeda)] (19), and [Cu(4,4'-Me 2bpy)2 ][Cu(XDK)] (20). All of these complexes were prepared by allowing 10 or 11 to react with 2-4 equiv or an excess of the
appropriate ancillary ligand, followed by washing with pentane or Et2 0 to remove
residual free ligand. All were recrystallized to afford analytically pure material.
Treatment of 10 with two equivalents of triphenylphosphine followed by recrystallization afforded bis(phosphine) adduct 13 as colorless blocks. Conductivity
measurements revealed 13 to be a non-electrolyte in CH 2Cl 2 solution. The 1H NMR
spectrum exhibited one set of XDK resonances and a complicated set of triphenylphosphine resonances in a 2:1 ratio. The proton-decoupled
13C
NMR spectrum
showed single sets of XDK and triphenylphosphine resonances, and phosphorus
coupling to three of the four phenyl ring proton resonances, as is found in free
triphenylphosphine in CD 2C12. The
3 1P
NMR spectrum showed one broad singlet at
room temperature, shifted slightly downfield from that of free triphenylphosphine
(8 5.1 ppm, Av1 /2 = 24.7 Hz, CD 2C12). X-ray structural analysis revealed solid 13 to be
composed two inequivalent trigonal planar copper atoms, with one copper displaced
laterally from the four-oxygen carboxylate plane and the other lying above the plane
(Figure 1.3). The copper-phosphorus bond lengths are normal for Cu(I) triphenylphosphine complexes having one phosphine ligand per copper atom. 49 Simple
Cu(I) carboxylate-triphenylphosphine complexes have been prepared and structurally characterized previously, with [Cu(OAc)(PPh 3 )2] being a representative example. 50 This mononuclear complex consists of a tetrahedrally coordinated copper
atom with a chelating acetate and two triphenylphosphine ligands. The dissimilar
reactivity of 10 is probably due to steric effects and the convergent nature of the XDK
carboxylate ligands.
Exposure of 10 to excess 2,6-dimethylphenylisocyanide followed by recrystallization provided the tris(isonitrile) adduct 14. The 1H NMR spectrum exhibited
single sets of cleanly shifted XDK and isonitrile resonances in the expected ratios.
The IR spectrum showed one broad isonitrile C-N stretch at 2134 cm
-1 .
The complex
is a non-electrolyte in CH 2C12 solution. X-ray structural analysis on two different
crystals, obtained under identical crystallization conditions, revealed that the
tris(isonitrile) complex can exist as two isomers (Figure 1.3). In all-terminal colorless
14a, one copper is trigonal and the other tetrahedral, essentially as found in a
bis(carboxylate) tris(isonitrile) complex prepared from Cu(I) benzoate and p-tolyl isocyanide.4 1 The other isomer, yellow 14b, has the isonitrile ligands coordinated in a
symmetrical fashion, with one bridging the two copper atoms and one terminal on
each. The bridging isonitrile in 14b enforces a relatively close Cu...Cu distance of
2.7278 (9)
A
compared to the value of 3.2560(5)
A
for 14a. A bridging isonitrile
derivative similar to 14b has not been reported for other Cu(I) carboxylates. The
isomers appear to be in rapid equilibrium in solution at room temperature since
only one set of 1H NMR resonances is observed for the XDK and isonitrile ligands.
Treatment of 10 with excess norbornene followed by recrystallization provided bis(norbornene) adduct 15 as colorless blocks. The X-ray structure was analogous to that determined for bis(triphenylphosphine) adduct 13, with each trigonal
planar copper atom ligated to XDK in a different fashion (Figure 1.3). Both norbornene ligands are coordinated via the exo face, as has been observed in other Cu(I)
norbornene adducts, with characteristic Cu(I)-olefin bond distances.5 1 When crystals
of 15 are allowed to dry fully under an atmosphere of N 2 at room temperature, one
of the norbornene ligands is lost, as judged by 1H NMR spectroscopy and elemental
analysis. This complex does not lose the remaining norbornene ligand when exposed to high vacuum. It is probably composed of trigonal planar and linear two coordinate copper atoms, although an X-ray structure has not been obtained.
Treatment of 10 with excess cyclohexene, followed by evaporation of the
volatile components under high vacuum, provided the desolvated parent complex
16. The 1H and
13C
NMR and IR spectra showed no cyclohexene or acetonitrile
peaks, and the product is a non-electrolyte in CH 2C12 solution. X-ray quality crystals
of 16 were grown from either CH2C12/pentane or PhCl/pentane. A low resolution
structure was obtained on crystals grown from CH2Cl2/pentane. (X-ray data for 16
from CH2C12/pentane: P21/n, a = 14.0015(3), b = 12.8639(2), c =22.3936(3), P = 106.621
(1), V = 3832.8 (1), Z = 4, T = 188 K, R = 0.121, wR 2 = 0.355. This structure was not fully
refined due to major disorder of the two lattice CH 2Cl 2 molecules.) This homoleptic
dinuclear complex consists of two nearly linear two coordinate copper ions with no
intermolecular bonding to any neighboring Cu 2 XDK (Scheme 2, n= 1). Structural
analysis of the crystals grown from PhCl/pentane showed that two {Cu 2XDK} units
in this isomer are linked by a bond between an XDK imide carbonyl oxygen and a
neighboring copper atom (Cu2-0504, Figure 1.4). One of the {Cu2XDK} units consists
of two linearly coordinated copper atoms with a Cu3..-Cu4 distance of 2.6106 (9)
A.
Each copper atom is pulled laterally out of the four-oxygen carboxylate plane. The
other Cu2XDK unit contains two- and three-coordinate copper atoms, with a slightly
shorter Cul...Cu2 distance of 2.5697 (8)
A. Instead of being displaced
in a lateral direc-
tion from the four-oxygen plane, the two-coordinate Cul atom lies slightly above
the plane, thus accounting for the slightly shorter Cu...Cu distance in this
(Cu2(XDK)} unit. These structures may be contrasted to those of polymeric Cu(I) acetate 52 and tetrameric Cu(I) benzoate,53 where oligomerization via the bridging carboxylate oxygen atoms occurs, presumably because of the greater conformational
flexibility of these ligands. Apparently the convergent nature of the XDK ligand
coupled with the chelate effect cause the carboxylate ligands to bind the copper ions
more tightly compared to simple Cu(I) carboxylates, thus inhibiting oligomerization.
Exposure of 10 to CO in THF or CH 2Cl 2 solution followed by solvent removal
afforded no product, as judged by IR and NMR spectroscopy. These results are in
contrast to the stable CO adducts obtained with Cu(I) benzoate and other simple car-
boxylates. 40 ,46 Carbon monoxide is a very poor sigma donor, and the Cu(I) ions in
the {Cu 2 (XDK} platform must also be unable to engage in n backbonding with this
ligand. Both factors preclude stable adduct formation.
Reaction of 10, 11, or 12 with excess tmeda followed by recrystallization from
THF/pentane provided mono(tmeda) adducts 17-19 as colorless blocks or needles.
These reactions do not occur for Cu(I) acetate or benzoate, which upon exposure to
excess tmeda under identical conditions immediately disproportionates to Cu metal
and uncharacterized Cu(II) products. An X-ray structure was obtained for 17. This
complex is composed of one linear two-coordinate copper, analogous to that observed for acetonitrile complex 10, and a tetrahedrally ligated copper with a chelating tmeda molecule. The Cu-..Cu distances in 10 and 17 are also nearly identical.
Because tmeda adducts 17-19 react with dioxygen at low temperature to afford
stable peroxo intermediates in some cases,4 3 detailed knowledge of their solution
properties was desired. Of particular interest was to determine whether the Cu(I)
ions remained coordinated to the XDK ligand in solution, and whether the tmeda
ligand exhibited fluxional behavior. All of the tmeda adducts are non-electrolytes in
CH 2C12 solution, even in the presence of a 20-fold excess of tmeda, confirming that
the Cu(I) ions remain coordinated to the carboxylates in solution. The 1H NMR
spectrum of each of the tmeda adducts exhibits a single set of XDK resonances, suggesting that the approximate Cs symmetry of the solid state structure of 17 may not
be maintained in solution. If it were, the pair of four-proton doublets assigned to the
XDK methylene groups (Hax and Heq, below) might split into four, two-proton doublets. This phenomenon has been observed for other asymmetrically ligated M2 XDK
and heterodimetallic MM'(XDK) complexes, when one of the mirror planes of the
C2v-symmetric XDK ligand is lost.43 The psuedo C2v-symmetric spectral pattern ob-
served for 17 suggests that the tmeda ligand exchanges between the two copper sites
in Cu 2 (XDK) by an intra- and/or intermolecular fashion, resulting in one set of averaged Hax and Heq resonances.
Additional
1H
NMR experiments were carried out to help elucidate the na-
ture of this exchange process. The 1H NMR spectrum of recrystallized 17 in the presence of one additional equiv of tmeda still displayed a single set of tmeda and XDK
resonances, slightly shifted from those in 17, suggesting that free and coordinated
tmeda exchange rapidly on the 1H NMR timescale. To determine whether the
tmeda ligand in 17 could be exchanging intermolecularly between different
{Cu 2 (XDK)} units, a 1H NMR spectrum of an equimolar mixture of 17 and parent
complex 16 was recorded at room temperature. The spectrum exhibited one set of
XDK and tmeda resonances, and the chemical shifts of the XDK resonances were the
average of those observed for pure 16 and 17. A variable temperature (VT) 1H NMR
spectroscopic study was carried out on pure 17. As the temperature was decreased,
the two sharp tmeda singlets (methyl and methylene protons) broadened and overlapped one another. The tmeda resonances appeared to coalesce between -70 and -80
'C. Below this temperature one broad singlet was observed for the tmeda methyl
groups, and the tmeda methylene resonances appeared to be split into two broad
singlets in an approximately 3:1 ratio. One sharp set of XDK resonances was observed down to -85 'C, accompanied by small changes in their chemical shifts. A
more detailed interpretation of the VT data was hampered by overlap of the tmeda
resonances with each other and with the XDK resonances. Although no detailed
mechanistic information could be gleaned from the VT experiments, the broadening and shifting of the tmeda resonances with decreasing temperature does support
the occurrence of some fluxional tmeda exchange process(es), perhaps involving
copper-nitrogen bond breaking and/or different conformations of the five-membered tmeda chelate ring. Taken together, these additional 1H NMR experiments
support the conclusion that the tmeda ligands in complexes 17-19 are exchanging
rapidly between copper sites, but do not reveal the mechanism.
Treatment of 10 with two equiv of 4,4'-dimethyldipyridine afforded 20 as a
dark brick-red solid. This color is characteristic of the [Cu(bpy)2]+ cation,5 4 and immediately suggested that one of the copper ions had been extracted from the
bis(carboxylate) platform. Neutral and ionic species may be in equilibrium, as indicated by eq 3. A similar equilibrium was suggested to explain the solution
[Cu 2(XDK)(4,4'-Me 2bpy) 2]
" [Cu(4,4'-Me 2bpy) 2] [Cu(XDK)]
(3)
behavior of [Cu(phen) 2 12[Cu(OAc)2], specifically based on its crystal structure and solution conductivity properties. 54,55 Determination of the molar conductivity from a
plot of the measured conductivity versus concentration for complex 20 in CH 2C12
solution (Figure 1.5) gave approximately the same value as those obtained for
Bu 4 NPF 6 and [Cu(MeCN) 4 ]C10 4 , consistent with the equilibrium in eq 3 lying
completely to the right. Suitable crystals of 20 could not be obtained for X-ray
crystallography. Based on the similarity of its UV-vis spectral features to those of
[Cu(phen)212[Cu(OAc)2] and its conductivity properties, 20 is probably composed of a
bis(dipyridyl) cation and a linear two coordinate Cu(XDK) anion.
Anionic Donors: Preparation of (Et 4N)[Cu(PXDK)] (21) and [CuLi(XDK)(THF) 2]
(22). We attempted to prepare a class of anionic-bridged dicopper(I) XDK complexes
in order to explore further the chemistry of this system. Attempts to synthesize thiolate- or cyanide-bridged {Cu 2 (XDK)} complexes from Et 4 N(SR) (R = Ph, Me) and
Et 4 N(CN), respectively, were unsuccessful. The former reagents invariably yielded
copper(I) sulfide and intractable XDK-containing products. Reaction of acetonitrile
adduct 11 with tetraethylammonium cyanide in CH 2C1 2 immediately resulted in
precipitation of Cu(I) cyanide and formation of 21, as judged by IR and 1H NMR
spectroscopic analyses. The solid state structure of 21 is composed of two crystallographically independent clusters which differ only in the orientation of the peripheral propyl groups. Each contains linear two-coordinate copper ligated by cis-carboxylate oxygen atoms. This mononuclear complex is unreactive toward additional
cyanide, attesting to the effectiveness of the XDK ligand for retaining the remaining
copper atom in the "skewered" two coordinate arrangement.
Alkyl- and aryl-bridged cuprate complexes of XDK were sought for studies of
conjugate addition and other R- transfer reactions. The only structurally characterized Cu(I) carboxylate-alkyl or aryl complex reported to date is [Cu3(g-Mes)(g0 2CPh) 2], a neutral trinuclear cluster isolated upon exposure of Cu(I) benzoate to
pentameric mesitylcopper(I). 56 No well characterized Cu(I) carboxylate alkyl or aryl
cuprates have been described. Treatment of 10 with one equiv of PhLi in THF afforded heterodimetallic complex 22 as the only XDK-containing product isolated,
even when a large excess of 12-crown-4 was added. Much difficulty was experienced
in trying to purify 22 from the phenylcopper(I) coproduct and large amounts of an
intractable brown material. As in the preparation of mononuclear 21, this complex
was obtained more conveniently from 10 and lithium cyanide. The solid state structure consists of a linear two coordinate copper atom and a tetrahedrally ligated
lithium atom bridged by XDK. Crystals of 22 lose one of the coordinated THF
molecules upon isolation and drying, as judged by integration of the 1H NMR spectrum and elemental analysis, presumably to afford [CuLi(XDK)(THF)]. The solid
state structure is unknown, but by analogy to other heterodimetallic alkali metal
XDK complexes,5
7
the lithium ion is probably coordinated to one or more of the
XDK imide carbonyl oxygens. Compounds 21 and 22 provided the ideal kinetic stability for the preparation of a host of Cu(I)/Cu(II) mixed valent and Cu(I)M(II) heterodimetallic bis(carboxylate)-bridged complexes, which are the subject of a separate
report. 32
Conclusions
A more sterically demanding version of XDK and PXDK has been prepared in
multigram quantities and high purity. The kinetic stability imparted by the convergent nature of the XDK ligand system provides an excellent template for the synthesis of discrete dinuclear Cu(I) complexes. All three XDK derivatives afford complexes, some heretofore unknown for Cu(I) carboxylates, of n acceptor and sigma
donor ligands. Disproportionation reactions which occur with the simple Cu(I) carboxylates are not observed with XDK. Attempts to prepare anionic-bridged Cu 2 XDK
complexes resulted instead in extrusion of one Cu(I) ion and formation of monocopper(I) XDK products.
Acknowledgement. This work was supported by a grant from the National
Science Foundation.
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Abbreviations used: H 2 XDK, m-xylylenediamine bis(Kemp's triacid imide);
H 2 PXDK, m-xylylenediamine bis(propyl Kemp's triacid imide); H 2 BXDK, mxylylenediamine bis(benzyl Kemp's triacid imide); NB, norbornene; tmeda,
N,N,N',N'-tetramethylethylenediamine; 4,4'-Me2bpy, 4,4'-dimethyl-2,2'dipyridine; phen, 1,10-phenanthroline.
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Table 1.1. Summary of X-ray Crystallographic Data.
formula
H 2 BXDK (6)
[Cu2(XDK)(MeCN)]
(10).1CH 3 CN
[Cu 2 (XDK)(PPh 3) 2 ]
(13).1PhCl
[Cu2(XDK)(ArNC) 3 ]
(14a).0.5PhC1
[Cu2(XDK)(g-ArNC)
(ArNC) 2 1
(14b)-0.5PhCl.1Et 2 0
C 6 2 H 6 4 N 20
C 3 6 H 4 4 N 4 08Cu 2
C 6 2 H 6 7 .5 N 5 0 8 C10 .5
Cu2
1155.51
P1
11.8747(2)
13.8800(2)
18.50390(10)
97.5001(9)
90.9158(10)
106.1093(8)
2900.64(7)
2
1.323
-85
0.814
0.857-1.000
3-57
17531
12211
8121
703
4.97
11.26
0.494, -0.463
C 6 6 H 77 .5 N 5 0 9C10 .5
Cu2
1229.64
965.15
P21/c
11.91550(10)
28.7491(4)
17.2033(2)
P21/c
13.6100(2)
16.1248(3)
17.69810(10)
C 74 H 7 3 N 2 0 8 C1P 2
Cu2
1342.81
C2/c
41.7699(6)
20.07040(10)
16.2744(2)
108.4970(10)
112.2098(7)
102.9530(10)
5588.72(11)
4
1.147
Pcalcd, g /cm 3
T, 0C
-85
jt(Mo Ka), mm- 1
0.075
transmission coeff
0.854-1.000
20 limits, deg
3-57
total no. of data
33729
no. of unique data
12738
observed dataa
9442
no. of parameters
959
R(%)b
5.15
wR2(%) c
11.26
max, min peaks, e/A3 0.302, -0.227
3595.83(9)
4
1.455
-85
1.239
0.828-1.000
3-46
13960
5089
4355
627
3.41
7.59
0.730, -0.633
13296.3(3)
8
1.342
-85
0.785
0.831-1.000
3-57
39721
15154
10375
797
5.67
15.25
1.039, -1.138
space group
a, A
b, A
c, A
ac, deg
3, deg
y, deg
V, '33
vA
Z
8
787.83
aObservation criterion: I>2(7(I). b R = X I IFo I- IFc I I/Z I Fo I. CwR 2 = {Z[w(Fo2-Fc2)2] /[w(Fo2)2]}1/2
P21/n
22.5777(3)
12.3144(2)
23.6382(4)
109.96(1)
6190.8(2)
4
1.319
-85
0.769
0.852-1.000
3-57
35986
14149
8708
728
8.00
21.65
1.240, -1.037
Table 1.1 (cont'd.) Summary of X-ray Crystallographic Data.
[Cu 2 (XDK)(NB) 2 ]
(15)-1Et 2 0
[Cu 2 (XDK)12
(16).1.5PhC1
formula
C 50 H 6 8N 2 0 9 Cu 2
fw
space group
a, A
968.14
P1
12.4880(7)
13.0087(8)
15.0250(9)
93.8052(8)
94.5239(11)
98.6628(10)
2397.9(2)
2
1.341
-85
0.943
0.736-1.000
3-46
9589
6570
5445
584
3.78
9.58
0.474, -0.378
C 7 3H 8 3. 5 N 4 0
Cu4
1580.27
Pl
13.7573(6)
16.5180(7)
17.8154(7)
67.6240(10)
70.5980(10)
89.0870(10)
3502.5(3)
2
1.498
-85
1.326
0.795-1.000
3-57
21334
14903
9646
862
6.14
14.92
0.960, -1.016
b,A
c, A
a, deg
P, deg
y, deg
V, A3
Pcalcd, g /cm 3
T, -C
g(Mo Ka), mm- 1
transmission coeff
20 limits, deg
total no. of data
no. of unique data
observed dataa
no. of parameters
b
R(%)
2
wR (%/o)c
max, min peaks, e/A 3
aObservation criterion: I>2a(I). b R =
I IFo I- IFc I I /
[Cu 2 (XDK)(tmeda)]
(17).2THF
1 6C11
.5 C 4 6 H 70 N 4 0
966.14
Pna21
21.3272(4)
18.0465(3)
12.4138(2)
10 Cu 2
(Et 4 N)[Cu(XDK)]
(21)-0.5CH 3 CN
[CuLi(XDK)(THF) 2 1
(22).1THF
C5 3 H 83. 5N 3 .50 8 Cul
C 4 4 H 6 2 N 2 0 1 1LiCu
961.27
P21
10.6886(2)
16.3952(3)
30.5770(1)
865.44
P1
11.75850(10)
12.11510(10)
16.73070(10)
102.1888(2)
96.4520(6)
108.5870(2)
2166.22(3)
2
1.327
-85
0.565
0.900-1.000
3-57
13402
9309
7405
736
5.37
14.18
1.150, -0.573
96.12(1)
4777.84(14)
4
1.343
-85
0.949
0.845-1.000
3-57
28775
9880
8203
512
5.01
12.87
0.834, -0.399
5327.87(14)
4
1.198
-85
0.463
0.856-1.000
3-57
33173
22720
16140
1179
5.21
13.99
0.482, -0.331
IFo I. cwR 2 = {E[w(Fo2-Fc2)2] / [w(F2)2] 1
/ 2.
Table 2.2. Selected Bond Distances and Angles.a
Distances
0101-C101
0102-C101
1.311(2)
1.222(2)
0201-C201
1.224(2)
0202-C201
1.308(2)
Angles
0102-C101-0101
0201-C201-0202
123.2(2)
123.09(14)
0101-.0201 2.651(2)
0102...0202 2.678(2)
13
14a
Cul.-.Cu2
2.6287(5)
Cul-0102
Cul-0202
1.857(2)
0102-Cul-0202
0101-Cu2-0201
0101-Cu2-N1
94.45(11)
0201-Cu2-N1
123.93(11)
138.07(10)
Cu2-0101
1.880(2)
2.002(2)
Cu2-0201
1.919(2)
Cu2-N1
1.989(3)
Cul...Cu2
Cul-0102
3.1171(6)
1.963(2)
0102-Cul-0202
0101-Cu2-0201
Cul-0202
Cu2-0101
1.957(2)
1.977(2)
0102-Cul-P1
0202-Cul-P1
Cu2-0201
Cul-P1
1.998(2)
2.2427(9)
0101-Cu2-P2
0201-Cu2-P2
Cu2-P2
2.1652(9)
Cul...Cu2
Cul-0102
Cul-0202
Cu2-0101
3.2560(5)
1.972(2)
1.981(2)
2.069(2)
Cu2-0201
172.00(8)
141.37(9)
116.93(10)
107.65(8)
113.79(7)
122.21(7)
120.81(7)
2.084(2)
0102-Cul-0202
0101-Cu2-0201
0102-Cul-C1
0202-Cul-C1
0101-Cu2-C2
110.96(12)
Cul-C1
Cu2-C2
1.842(3)
0201-Cu2-C2
111.09(12)
1.877(3)
0101-Cu2-C3
98.83(11)
Cu2-C3
C1-N1
C2-N2
1.930(3)
0201-Cu2-C3
97.12(11)
1.157(4)
1.158(4)
C1-N1-C4
176.1(3)
C2-N2-C12
172.9(3)
117.80(10)
107.41(10)
119.77(12)
121.82(12)
Table 2.2. (cont'd.) Selected Bond Distances and Angles.a
Distances
Angles
14a
C3-N3
1.156(4)
C3-N3-C20
168.0(3)
14b
Cul...Cu2
Cul-0102
Cul-0202
Cu2-0101
Cu2-0201
Cul-C1
Cul-C2
Cu2-C2
Cu2-C3
2.7278(9)
2.059(3)
2.035(3)
2.071(3)
2.022(3)
1.921(7)
2.001(6)
2.135(5)
1.908(6)
0102-Cul-0202
0101-Cu2-0201
0102-Cul-C1
0102-Cul-C2
0101-Cu2-C2
0101-Cu2-C3
C1-N1-C4
C2-N2-C12
C3-N3-C20
114.05(13)
117.56(13)
Cul...Cu2
Cul-0102
Cul-0202
Cu2-0101
Cu2-0201
Cul-C8
Cul-C9
Cu2-C1
Cu2-C2
3.4211(6)
1.965(2)
1.963(2)
1.978(2)
1.981(2)
2.070(4)
2.076(4)
2.023(4)
2.033(3)
0102-Cul-0202
0101-Cu2-0201
0102-Cul-C8
0102-Cul-C9
0101-Cu2-C1
0101-Cu2-C2
126.86(10)
Cul...Cu2
Cu3-.Cu4
Cul-0102
Cul-0202
Cu2-0101
Cu2-0201
Cu2-0504
Cu3-0402
Cu3-0502
2.5697(8)
2.6106(9)
1.855(3)
1.859(3)
1.970(3)
1.942(3)
2.191(3)
1.873(3)
1.871(3)
0102-Cul-0202
0101-Cu2-0201
0101-Cu2-0504
0201-Cu2-0504
0402-Cu3-0502
0401-Cu4-0501
168.9(2)
15
16
109.1(2)
99.3(2)
99.1(2)
98.8(2)
173.1(6)
175.3(5)
172.0(5)
105.17(9)
133.95(13)
96.70(13)
108.2(2)
146.6(2)
160.85(12)
94.65(11)
98.50(12)
170.87(14)
165.8(2)
Table 2.2. (cont'd.) Selected Bond Distances and Angles.a
Distances
Angles
Cu4-0401
Cu4-0501
1.875(3)
1.869(3)
Cul...Cu2
Cul-0102
Cul-0202
Cu2-0101
Cu2-0201
Cu2-N1
Cu2-N2
2.6245(7)
1.857(3)
1.859(3)
2.014(3)
1.999(3)
2.165(3)
2.201(4)
0102-Cul-0202
0101-Cu2-0201
0101-Cu2-N1
0101-Cu2-N2
0201-Cu2-N1
0201-Cu2-N2
Cul-0102
Cul-0202
1.850(3)
1.848(3)
0102-Cul-0202
176.70(14)
Cul...Lil
Cul-0102
Cul-0202
Lil-0101
Lil-0201
Li-O1
Lil-02
3.023(4)
1.855(2)
1.862(2)
1.901(5)
1.908(5)
1.986(5)
1.971(5)
0102-Cul-0202
0101-Lil-0201
171.63(8)
175.4(2)
143.36(11)
99.50(13)
105.32(13)
101.63(13)
106.25(14)
0101-Lil-01
128.3(3)
106.0(2)
0101-Lil-02
107.0(2)
0201-Lil-01
0201-Lil-02
104.5(2)
103.9(2)
aNumbers in parentheses are estimated standard deviations of the last significant
figure. Atoms are labeled as indicated in Figures 1-4.
Table 1.3. Atomic coordinates (x 10 4 ) and equivalent
isotropic displacement parameters (A2 x 10 3 ) for 6. a
atom
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(119)
C(120)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(127)
C(128)
C(129)
C(130)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
x
1173(1)
1818(1)
1470(1)
1840(1)
-1655(1)
-185(1)
-251(1)
-1353(1)
-1014(1)
-845(1)
1505(1)
-1147(1)
-323(1)
2853(2)
351(2)
-1373(2)
1564(1)
1483(1)
220(1)
-545(1)
-616(1)
640(1)
3158(1)
3562(2)
3771(2)
3616(2)
3246(2)
3008(2)
-760(1)
-1015(2)
-2013(2)
-2786(2)
-2546(2)
-1536(2)
-2635(2)
-3542(2)
-4700(2)
-4979(2)
-4106(2)
-2935(2)
1695(1)
-840(1)
-225(1)
3206(1)
445(2)
-729(2)
y
8450(1)
8145(1)
9234(1)
8929(1)
8158(1)
7542(1)
9023(1)
9666(1)
7821(1)
9362(1)
8100(1)
7833(1)
7496(1)
7655(1)
6669(1)
7342(1)
7633(1)
7231(1)
7098(1)
7001(1)
7433(1)
7576(1)
7252(1)
6832(1)
6455(1)
6503(1)
6923(1)
7295(1)
6478(1)
6568(1)
6387(1)
6113(1)
6013(1)
6191(1)
7191(1)
7516(1)
7383(1)
6922(1)
6593(1)
6725(1)
9281(1)
9721(1)
9363(1)
9887(1)
9855(1)
10582(1)
z
5419(1)
4447(1)
4696(1)
3613(1)
4993(1)
3094(1)
1891(1)
3939(1)
4022(1)
2884(1)
5054(1)
4804(1)
3754(1)
6127(1)
3836(1)
5955(1)
5487(1)
4887(1)
4341(1)
4887(1)
5385(1)
5933(1)
6719(1)
6518(1)
7052(2)
7805(2)
8026(1)
7485(1)
3222(1)
2390(1)
1813(1)
2067(1)
2890(1)
3464(1)
5535(1)
5290(2)
4917(2)
4776(2)
5019(2)
5404(1)
4054(1)
3442(1)
2309(1)
4270(1)
1348(1)
3679(1)
U(eq)
34(1)
32(1)
30(1)
27(1)
35(1)
31(1)
31(1)
31(1)
22(1)
22(1)
25(1)
24(1)
22(1)
33(1)
28(1)
30(1)
25(1)
26(1)
23(1)
24(1)
24(1)
27(1)
34(1)
42(1)
54(1)
56(1)
53(1)
45(1)
27(1)
33(1)
39(1)
40(1)
38(1)
32(1)
30(1)
51(1)
69(1)
71(1)
66(1)
46(1)
22(1)
22(1)
23(1)
27(1)
29(1)
27(1)
Table 1.3.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 6. a
atom
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(219)
C(220)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
C(227)
C(228)
C(229)
C(230)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
x
1904(1)
1747(1)
444(1)
-150(1)
-162(1)
1122(1)
4195(1)
4496(2)
5453(2)
6111(2)
5820(2)
4867(2)
-758(2)
-1205(2)
-2317(2)
-3007(2)
-2573(2)
-1457(2)
-1933(2)
-2037(2)
-3131(2)
-4144(2)
-4058(2)
-2961(2)
-995(1)
-1516(1)
-2645(1)
-3204(2)
-2704(1)
-1585(1)
-3234(2)
-3341(2)
y
9758(1)
9767(1)
9806(1)
10223(1)
10163(1)
10127(1)
9557(1)
9189(1)
8898(1)
8979(1)
9347(1)
9629(1)
9934(1)
10383(1)
10462(1)
10092(1)
9645(1)
9567(1)
10734(1)
11072(1)
11236(1)
11059(1)
10726(1)
10564(1)
8596(1)
8943(1)
8889(1)
8464(1)
8103(1)
8182(1)
9271(1)
7648(1)
z
3743(1)
2818(1)
2246(1)
2504(1)
3382(1)
3965(1)
4273(1)
4824(1)
4845(1)
4339(2)
3791(2)
3759(1)
724(1)
546(1)
-7(2)
-396(1)
-237(1)
314(1)
3140(1)
2551(1)
2075(2)
2171(2)
2763(2)
3240(2)
3455(1)
2906(1)
2351(1)
2352(1)
2890(1)
3446(1)
1765(1)
2861(2)
U(eq)
22(1)
24(1)
23(1)
24(1)
23(1)
24(1)
28(1)
37(1)
50(1)
60(1)
55(1)
40(1)
31(1)
45(1)
63(1)
62(1)
52(1)
39(1)
31(1)
51(1)
69(1)
73(1)
70(1)
48(1)
23(1)
22(1)
28(1)
33(1)
29(1)
22(1)
40(1)
49(1)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.4. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 10.a
atom
Cu(i)
Cu(2)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
N(1)
N(2)
0(101)
0(102)
0(201)
0(202)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
x
3694(1)
2209(1)
-36(2)
2780(2)
5084(2)
2356(2)
1348(2)
3732(2)
1509(3)
3250(4)
1296(2)
2641(2)
3287(2)
4622(2)
1658(3)
305(3)
1861(3)
801(3)
1611(3)
-1509(3)
882(3)
1313(3)
1201(3)
38(3)
-346(3)
-230(3)
4233(3)
3309(3)
4823(3)
5475(3)
6622(3)
3605(3)
4979(3)
5877(3)
5604(3)
5119(3)
4104(3)
4371(3)
2532(3)
3012(3)
2840(3)
2197(3)
1712(3)
1890(3)
3348(3)
1000(3)
y
5078(1)
5613(1)
6313(2)
5087(2)
7255(2)
8201(2)
5703(2)
7721(2)
5007(3)
3795(3)
5108(2)
4413(1)
6440(2)
5874(2)
4552(2)
5704(2)
5022(2)
3218(2)
3819(3)
5176(3)
3947(2)
3629(2)
4239(2)
4483(2)
4918(2)
4321(2)
6432(2)
8136(2)
7607(2)
6691(2)
8185(2)
9281(2)
7097(2)
7330(2)
7966(2)
8733(2)
8507(2)
7880(2)
6721(2)
7493(2)
8060(2)
7816(2)
7040(2)
6501(2)
8908(2)
6812(3)
z
U(eq)
-505(1)
-15(1)
-2632(2)
-2943(2)
-1245(2)
-614(2)
-2826(2)
-915(2)
624(2)
2339(3)
-1083(1)
-1225(1)
439(2)
173(2)
-1401(2)
-2841(2)
-3015(2)
-1471(2)
-3940(2)
-3570(2)
-2007(2)
-2641(2)
-3337(2)
-3756(2)
-3153(2)
-2444(2)
491(2)
-404(2)
-748(2)
1877(2)
-97(3)
602(2)
1024(2)
739(2)
40(2)
262(2)
386(2)
1092(2)
-1878(2)
-1732(2)
-2363(2)
-3145(2)
-3317(2)
-2663(2)
-2208(3)
-4178(2)
28(1)
38(1)
34(1)
36(1)
41(1)
37(1)
24 (1)
25(1)
59(1)
81(2)
31(1)
30(1)
35(1)
31(1)
24(1)
26(1)
26(1)
34(1)
43(1)
41(1)
25(1)
30(1)
29(1)
31(1)
28(1)
29(1)
26(1)
28(1)
29(1)
37(1)
43(1)
41(1)
28(1)
31(1)
29(1)
33(1)
29(1)
32(1)
25(1)
25(1)
29(1)
32(1)
28(1)
25(1)
41(1)
40(1)
59
Table 1.4.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 10
atom
x
y
3
) for 10.a
z
U(eq)
C(1)
C(2)
C(3)
1136(3)
679(4)
3844(4)
4445(3)
3723(3)
4089(3)
820(3)
1057(3)
2093(3)
48(1)
57(1)
55(1)
C(4)
4609(4)
4463(3)
1813(3)
63(1)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.5. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 13. a
atom
Cu (1)
Cu(2)
P(1)
P(2)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
x
1481(1)
826(1)
1865(1)
499(1)
839(1)
1242(1)
1145(1)
1509(1)
828(1)
1731(1)
2131(1)
1285(1)
1273(1)
1721(1)
989(1)
938(1)
1438(1)
656(1)
1462(1)
450(1)
839(1)
1099(1)
1236(1)
953(1)
733(1)
587(1)
1383(1)
1505(1)
1983(1)
1406(1)
2443(1)
1439(2)
1527(1)
1904(1)
2065(1)
1940(1)
1568(1)
1396(1)
1493(1)
1687(1)
1861(1)
1835(1)
1645(1)
1474(1)
2075(1)
1632(1)
y
2368(1)
2110(1)
2432(1)
1548(1)
3095(1)
3218(1)
1647(1)
1558(1)
4031(1)
4475(1)
2255(1)
1983(2)
4236(1)
2117(2)
3412(2)
4308(2)
4557(2)
3878(2)
5562(2)
5048(2)
4074(2)
4603(2)
5008(2)
5304(2)
4754(2)
4357(2)
1376(2)
1721(2)
1874(2)
170(2)
1069(3)
700(3)
734(2)
742(2)
1136(2)
868(2)
975(2)
601(2)
3177(2)
2827(2)
3161(2)
3846(2)
4214(2)
3866(2)
2778(3)
4966(2)
z
1940(1)
2504(1)
1176(1)
1529(1)
2502(1)
1815(2)
3426(1)
2622(2)
4155(2)
3157(2)
4200(2)
5485(2)
3626(2)
4889(2)
2046(2)
3622(2)
3074(2)
759(3)
2214(3)
3294(3)
1661(2)
1599(2)
2410(2)
2742(3)
2945(2)
2139(2)
3220(2)
5227(2)
4556(2)
3049(3)
4849(4)
6028(3)
3681(2)
3892(3)
4684(3)
5426(3)
5279(2)
4475(2)
4267(2)
4929(2)
5650(2)
5671(2)
5016(2)
4315(2)
6369(3)
5053(3)
U(eq)
40(1)
38(1)
34(1)
37(1)
39(1)
50(1)
39(1)
50(1)
50(1)
49(1)
62(1)
58(1)
36(1)
40(1)
37(1)
38(1)
41(1)
59(1)
60(1)
55(1)
42(1)
45(1)
44(1)
47(1)
41(1)
45(1)
38(1)
47(1)
47(1)
58(1)
79(2)
80(2)
43(1)
50(1)
53(1)
63(1)
55(1)
50(1)
37(1)
41(1)
49(1)
54(1)
45(1)
37(1)
67(1)
61(1)
Table 1.5.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 13. a
atom
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C(28)
C(29)
C(30)
C(31)
C(32)
C(33)
C(34)
C(35)
C(36)
C(37)
C(38)
C(39)
C(40)
C(41)
C(42)
Cl(1)
x
456 (1)
413 (1)
388 (1)
395 (1)
435 (1)
471 (1)
639 (1)
458 (1)
589 (1)
891 (1)
1069 (1)
949 (1)
80 (1)
24 (1)
-294 (1)
-552 (1)
-500 (1)
-184 (1)
1724 (1)
1855 (1)
1742 (1)
1497 (1)
1360 (1)
1470 (1)
2106 (1)
2152 (1)
2342 (1)
2477 (1)
2430 (1)
2246 (1)
2177 (1)
2081 (1)
2303 (1)
2624 (1)
2727 (1)
2503 (1)
348 (2)
174 (2)
335 (3)
682 (2)
800 (2)
662 (1)
166 (1)
y
663 (2)
167 (2)
-497 (2)
-662 (2)
-180 (2)
482 (2)
1544 (2)
1810 (2)
1807 (3)
1523 (3)
1268 (2)
1278 (2)
1856 (2)
2505 (2)
2767 (2)
2385 (2)
1740 (2)
1473 (2)
2432 (2)
2027 (2)
2058 (3)
2496 (3)
2895 (2)
2863 (2)
3194 (2)
3492 (2)
4066 (2)
4350 (2)
4064 (2)
3490 (2)
1780 (2)
1142 (2)
621 (2)
729 (2)
1365 (2)
1884 (2)
3646 (3)
3283 (5)
2606 (6)
2395 (6)
2896 (3)
3456 (3)
4329 (1)
z
1745(2)
1139(3)
1365(3)
2179(4)
2785(3)
2573(3)
545(2)
-196(3)
-911(3)
-896(4)
-166(3)
559(3)
1249(2)
1460(3)
1258(3)
850(2)
639(3)
836(2)
22(2)
-510(2)
-1377(3)
-1724(3)
-1210(3)
-330(3)
1363(2)
2147(2)
2321(3)
1710(3)
922(3)
748(2)
1361(2)
1543(2)
1656(2)
1607(2)
1446(2)
1323(2)
5924(4)
6398(5)
6817(8)
6721(5)
6274(4)
5843(3)
5434(1)
U(eq)
42(1)
59(1)
74(1)
76(1)
69(1)
55(1)
42(1)
62(1)
82(2)
76(2)
67(1)
56(1)
37(1)
51(1)
59(1)
52(1)
55(1)
49(1)
40(1)
49(1)
64(1)
74(1)
71(1)
55(1)
36(1)
50(1)
63(1)
56(1)
50(1)
44(1)
32(1)
41(1)
44(1)
46(1)
46(1)
40(1)
88(2)
128(3)
182(4)
162(4)
91(2)
73(1)
126(1)
62
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.6. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 14a.a
atom
Cu (1)
Cu(2)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
N(1)
N(2)
N(3)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
x
526(1)
-441(1)
721(2)
1236(2)
528(2)
1066(2)
3320(2)
4130(2)
3861(2)
3104(2)
3693(2)
3471(2)
-1012(2)
-2369(2)
-540(2)
1061(3)
3278(3)
3739(3)
-80(3)
4035(3)
3020(3)
1171(3)
2009(3)
3319(3)
3506(3)
2821(3)
1510(3)
818(3)
3011(3)
3404(3)
-551(3)
3356(4)
2638(3)
758(3)
1480(3)
2806(3)
2986(3)
2440(3)
1111(3)
3587(3)
4144(3)
5347(3)
5977(3)
5458(3)
4253(3)
5947(3)
y
z
U(eq)
1357(1)
2072(1)
1258(2)
669(2)
3412(2)
2856(2)
2134(2)
852(2)
3961(2)
5202(2)
1482(2)
4587(2)
130(2)
866(2)
3030(2)
633 (2)
1382(3)
671(2)
-1051(3)
-1029(3)
377(3)
-329(2)
-840(2)
-388(2)
-345(3)
318(2)
-127(3)
3511(2)
5224(2)
4528(2)
4292(3)
5462(3)
6899(2)
4495(2)
4710(2)
5220(2)
6184(2)
5936(2)
5428(2)
3037(2)
3997(2)
4421(2)
3847 (3)
2882(3)
2494(2)
5476(3)
8260(1)
6822(1)
6480(1)
7468(1)
7451(1)
8449(1)
5574(1)
7577(1)
9114(1)
7071(1)
6572(1)
8096(1)
9276(1)
7675(2)
5423(1)
6791(2)
5842(2)
6949(2)
6263 (2)
6831(2)
4615(2)
6302(2)
6639(2)
6532(2)
5719(2)
5429(2)
5527(2)
8119(2)
7723(2)
8852(2)
8742 (2)
10081(2)
7810(2)
8589(2)
9322(2)
9299(2)
8954(2)
8173(2)
8189(2)
7334(2)
7686(2)
7665(2)
7267(2)
6900(2)
6945(2)
8043 (2)
33(1)
29(1)
40(1)
39(1)
38(1)
38(1)
49(1)
39(1)
39(1)
45(1)
28(1)
29(1)
34(1)
40(1)
34(1)
31(1)
34(1)
30(1)
49(1)
43(1)
50(1)
33(1)
35(1)
31(1)
36(1)
34(1)
37(1)
30(1)
33(1)
31(1)
45(1)
50(1)
45(1)
31(1)
34(1)
33(1)
38(1)
33(1)
34(1)
29(1)
30(1)
37(1)
41(1)
36(1)
28(1)
56(1)
Table 1.6.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A 2 x 103) for 14a.a
atom
(308)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(14)
(15)
(16)
(17)
(18)
(19)
(20)
(21)
(22)
(23)
(24)
(25)
(26)
(27)
1(1)
(28)
(29)
(30)
x
y
6165(3)
-437(3)
-1614(3)
-600(3)
-1649(3)
-2053(3)
-2633(4)
-2817(4)
-2436(4)
-1836(3)
-1415(4)
-1881(4)
-3179(3)
-3765(3)
-4520(3)
-4672 (3)
-4091(3)
-3327(3)
-2668(4)
-3595(4)
-212(3)
962(3)
1285(3)
482(4)
-669(3)
-1052(3)
-2310(3)
1839(3)
5235(3)
5058(5)
5048(5)
4991(5)
2290(3)
606(2)
1321(3)
2637(2)
-411(3)
114(3)
-454(4)
-1471(4)
-1967(3)
-1457(3)
-2016(3)
1233 (3)
261(3)
733 (3)
106(3)
-927(3)
-1366(3)
-782(3)
-1239(3)
1851(3)
3554(2)
3764(2)
4281(3)
4598(3)
4387(2)
3843(2)
3592(3)
3455(3)
6700(4)
5761(6)
5938(5)
5132(8)
z
6456
8878
7360
5940
9796
10378
10904
10836
10246
9711
9065
10425
8090
8607
9029
8937
8408
7974
7400
8705
4824
4652
4065
3680
3866
4440
4636
5098
6246
5582
4830
4275
U(eq)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(5)
(5)
(3)
51 (1)
34 (1)
36 (1)
33 (1)
34 (1)
45 (1)
61 (1)
68 (1)
61 (1)
42 (1)
64 (1)
67 (1)
35 (1)
38 (1)
43 (1)
46 (1)
43 (1)
38 (1)
59 (1)
55 (1)
29 (1)
36 (1)
48 (1)
49 (1)
41 (1)
32 (1)
47 (1)
58 (1)
172 (2)
105 (2)
103 (2)
101 (2)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.7. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 14b.a
atom
Cu(1)
Cu(2)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
N(1)
N(2)
N(3)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
x
7335(1)
8362(1)
7881(2)
7059(2)
8097(1)
7208(2)
7404(2)
5732(2)
5863(1)
7510(1)
6583(2)
6689(2)
6306(2)
8525(2)
9661(2)
7435(3)
7098(2)
6174(2)
7838(4)
5682(3)
7533(3)
7408(3)
6741(3)
6307(2)
6611(2)
7228(2)
7673(2)
7631(2)
7224(2)
6311(2)
8052(3)
5877(3)
7699(3)
7600(2)
6947(2)
6486(2)
6794(2)
7389(2)
7865(2)
6632(2)
6471(2)
6096(2)
5900(2)
6055(2)
6420(2)
5908(2)
y
1501(1)
2495(1)
3887(3)
3065(3)
1748(2)
1054(3)
6193(3)
4447(3)
1606(2)
3210(2)
5294(3)
2385(3)
-106(4)
1386(3)
3565(4)
3831(4)
6009(3)
5054(3)
4322(6)
5733(5)
7649(4)
4745(4)
4901(4)
5596(4)
6689(4)
6548(4)
5830(4)
1119(3)
2377(3)
1485(3)
-645(4)
-251(4)
1534(4)
261(3)
-232(3)
411(3)
630(4)
1303(3)
680(3)
3843(3)
3447(3)
4029(3)
5053(3)
5489(3)
4867(3)
3583(4)
z
U(eq)
247(1)
122(1)
195(2)
332(2)
-688(1)
-615(1)
-701(1)
-486(2)
-1773(1)
-2114(2)
-574(1)
-1948(1)
343(2)
1319(2)
539(2)
398(2)
-382(2)
-260(2)
1457(2)
465(3)
221(3)
839(2)
857(2)
348(2)
343(2)
227(2)
721(2)
-854(2)
-2127(2)
-1936(2)
-975(2)
-2426(3)
-2824(2)
-1342(2)
-1631(2)
-2150(2)
-2622(2)
-2351(2)
-1820(2)
-1265(2)
-1844(2)
-2340(2)
-2231(2)
-1662(2)
-1180(2)
-2969(2)
47(1)
49(1)
56(1)
56(1)
41(1)
45(1)
48(1)
49(1)
44(1)
44(1)
30(1)
31(1)
70(1)
48(1)
49(1)
50(1)
35(1)
37(1)
88(2)
64(2)
63(2)
55(1)
53(1)
44(1)
42(1)
42(1)
53(1)
38(1)
33(1)
35(1)
56(1)
62(1)
54(1)
40(1)
44(1)
43(1)
45(1)
39(1)
40(1)
29(1)
30(1)
32(1)
36(1)
36(1)
29(1)
43(1)
Table 1.7.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A 2 x 103) for 14b.a
atom
C(308)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
C(19)
C(20)
C(21)
C(22)
C(23)
C(24)
C(25)
C(26)
C(27)
C1(1)
C(32)
C(33)
C(34)
0(1)
C(28)
C(29)
C(30)
C(31)
y
x
5837
6746
8220
9197
5755
5568
5019
4672
4889
5424
5665
5946
8868
9325
9647
9512
9052
8720
8214
9455
10167
10056
10552
11119
11216
10740
10825
9429
4796
4927
5421
5492
8246
9278
8832
7795
7249
(2)
(3)
(3)
(2)
(3)
(3)
(4)
(4)
(3)
(3)
(4)
(4)
(2)
(2)
(2)
(3)
(3)
(3)
(4)
(3)
(2)
(3)
(3)
(3)
(3)
(2)
(3)
(3)
(3)
(4)
(4)
(4)
(4)
(7)
(7)
(8)
(6)
6606(4)
512(5)
1566(4)
3066(4)
-785(4)
-1108(5)
-1723(5)
-2018(5)
-1687(5)
-1071(5)
-725(6)
-768(7)
1087(4)
1794(4)
1458(5)
503(6)
-161(6)
118(5)
-605(6)
2868(5)
4296(5)
5333(5)
6063(5)
5780(7)
4760(7)
3967(5)
2834(5)
5632(5)
5971(4)
5442(7)
5784(8)
5296(8)
-3031(6)
-3190(13)
-3430(12)
-3228(12)
-2801(10)
z
-1570 (2)
393 (3)
826 (2)
391 (2)
210 (3)
692 (3)
551 (4)
-37 (4)
-505 (3)
-386 (3)
-874 (3)
1314 (3)
1919 (2)
2280 (2)
2862 (2)
3074 (2)
2719 (3)
2123 (2)
1701 (4)
2048 (3)
695 (2)
875 (2)
1007 (3)
964 (3)
792 (3)
649 (2)
468 (3)
915 (3)
-3912 (2)
-4505 (5)
-4662 (6)
-5218 (6)
2418 (3)
2320 (7)
2658 (7)
2741 (7)
2370 (6)
U(eq)
51 (1)
70 (2)
55 (1)
49 (1)
61 (1)
75 (2)
85 (2)
86 (2)
77 (2)
68 (2)
82 (2)
100 (2)
47 (1)
51 (1)
59 (1)
69 (2)
77 (2)
68 (2)
114 (3)
76 (2)
52 (1)
56 (1)
71 (2)
73 (2)
71 (2)
58 (1)
75 (2)
72 (2)
126 (2)
114 (3)
124 (4)
124 (4)
140 (3)
176 (5)
168 (5)
172 (5)
141 (4)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.8. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 15. a
atom
Cu(2)
Cu (1)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(1)
C(2)
x
y
976(1)
2591(1)
-26(2)
1156(2)
1640(2)
3037(2)
-1629(2)
879(2)
3664(2)
888(2)
-375(2)
2285(2)
217(3)
-1375(3)
10(3)
-693(3)
-550(4)
-3278(3)
-695(3)
-464(3)
-741(3)
-1924(3)
-2097(3)
-1814(3)
2617(3)
1852(3)
3398(3)
3768(3)
5287(3)
2180(3)
3379(3)
4381(3)
4196(3)
3743(3)
2653(3)
2798(3)
956(2)
1540(2)
1417(3)
708(3)
133 (3)
267(2)
2033(3)
-634(3)
859(4)
1537(4)
5981(1)
7789(1)
6718(2)
8155(2)
5145(2)
6410(2)
6162(2)
9050(2)
6552(2)
3872(2)
7608(2)
5205(2)
7679(3)
7077(2)
8684(2)
8579(3)
10426(3)
7179(3)
8349(3)
9384(3)
9326(2)
8819(3)
7718(3)
7751(3)
5471(3)
4180(2)
5653(3)
4506(3)
5301(4)
2349(3)
4649(3)
5045(3)
4943(3)
3821(3)
3482(3)
3596(3)
6411(2)
5830(2)
5813(3)
6419(3)
7037(2)
7010(2)
5160(3)
7693 (3)
6359(4)
5661(3)
U(eq)
z
5196
6674
5861
6319
6080
6511
7688
8389
8697
8038
8014
8352
6077
7601
8008
4955
7995
7079
5951
6536
7518
7525
7076
6097
6372
8036
8420
5524
8696
7838
6473
7136
8131
8267
7714
6714
8193
8737
9651
10002
9487
8572
10235
9897
3911
3990
(1)
(1)
(2)
(2)
(1)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(2)
28 (1)
36 (1)
33 (1)
38 (1)
34 (1)
38 (1)
39 (1)
40 (1)
46 (1)
36 (1)
25 (1)
26 (1)
28 (1)
29 (1)
31 (1)
44 (1)
52 (1)
51 (1)
31 (1)
36 (1)
35 (1)
39 (1)
34 (1)
35 (1)
29 (1)
29 (1)
33 (1)
43 (1)
54 (1)
49 (1)
31 (1)
35 (1)
36 (1)
41 (1)
35 (1)
36 (1)
25 (1)
26 (1)
30 (1)
33 (1)
31 (1)
26 (1)
42 (1)
45 (1)
57 (1)
48 (1)
Table 1.8.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 15. a
atom
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
0(1)
C(15)
C(16)
C(17)
C(18)
x
2638(3)
2610(4)
1557(4)
1828(4)
2599(4)
4073(3)
3270(3)
3424(3)
3858(3)
4723(3)
5372(3)
4463(3)
6568(4)
6222(5)
6625(7)
6834(6)
6643(5)
y
6202(3)
7250(4)
7365(3)
7168(4)
6379(3)
8643(3)
9234(3)
10104(3)
9569(3)
9135(3)
10167(3)
10835(3)
10099(4)
8327(6)
9456(6)
11166(5)
11848(4)
z
3835(3)
4222(3)
3731(3)
2744(3)
2831(3)
7180(3)
7307(3)
6690(3)
5904(3)
6479(3)
6975(4)
7114(4)
9554(3)
9726(4)
10162(4)
9939(5)
9240(3)
U(eq)
54(1)
70(2)
74(2)
69(1)
52(1)
46(1)
45(1)
47(1)
53(1)
53(1)
64(1)
64(1)
116(2)
111(2)
123(3)
122(2)
90(2)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.9. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 16. a
atom
Cu (1)
Cu(2)
Cu(3)
Cu(4)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
0(401)
0(402)
0(501)
0(502)
0(403)
0(404)
0(503)
0(504)
N(401)
N(501)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
x
5019(1)
4018(1)
617(1)
1361(1)
2812(2)
3765(2)
5432(2)
6270(2)
1696(2)
3547(3)
6727(3)
5278(3)
2695(3)
5994(3)
1597(3)
970(3)
924(2)
392(2)
4054(3)
3247(3)
2363 (2)
3210(2)
3638(3)
2799(3)
2908(3)
1776(3)
2809(4)
1747(4)
1975(5)
-126(4)
1938(3)
2100(4)
1952(4)
912(4)
885(3)
981(3)
6246(3)
6034(4)
6843(3)
7783(4)
8734(4)
7138(4)
7305(3)
8032(3)
7883(3)
7949(4)
y
8923(1)
7367(1)
6239(1)
7272(1)
8014(2)
9318(2)
7076(2)
8453(2)
6957(2)
9448(2)
8313(2)
5607(2)
8227(2)
6968(2)
8100(2)
7215(2)
6289(2)
5369(2)
8443(2)
6605(2)
4136(2)
6104(2)
7537(2)
5104(2)
8818(3)
7750(3)
9134(3)
9726(3)
10488(3)
7656(3)
9260(3)
9971(3)
9663(3)
9077(3)
8274(3)
8592(3)
7621(3)
6150(3)
7644(3)
7461(3)
7982(4)
4972(3)
7275(3)
7776(3)
7468(3)
6471(3)
z
U(eq)
759(1)
1436(1)
853(1)
1388(1)
1651(2)
1181(2)
1214(2)
555(2)
3849(2)
3362(2)
2565(2)
3120(2)
3465(2)
2821(2)
258(2)
-209(2)
2445(2)
1960(2)
-286(2)
-1391(2)
1523(2)
2484(2)
-846(2)
2015(2)
1536(3)
3581(3)
3296(3)
912(3)
3265(4)
3969(3)
1774(3)
2103(3)
3066(3)
3625(3)
3398(3)
2449(3)
852(3)
2739(3)
2440(3)
-243(3)
2000(4)
2596(4)
731(3)
950(3)
1918(3)
2293(3)
33(1)
28(1)
32(1)
35(1)
24(1)
31(1)
28(1)
39(1)
31(1)
39(1)
38(1)
37(1)
22(1)
25(1)
33(1)
34(1)
29(1)
29(1)
37(1)
36(1)
32(1)
27(1)
24(1)
21(1)
23(1)
23(1)
27(1)
31(1)
45(1)
39(1)
22(1)
28(1)
30(1)
31(1)
25(1)
24(1)
26(1)
29(1)
27(1)
36(1)
43(1)
42(1)
26(1)
29(1)
31(1)
33(1)
Table 1.9. (con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 16. a
atom
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
C(509)
C(510)
C(511)
C(512)
C(601)
C(602)
C(603)
C(604)
C(605)
C(606)
C(607)
C(608)
Cl(1)
C(1)
C(2)
C(3)
x
7079(3)
7206(4)
4326(3)
5062(3)
4938(4)
4057(4)
3316(3)
3462(3)
5735(4)
2396(4)
1406(3)
3792(3)
3350(3)
680(4)
3464(5)
4376(4)
1701(4)
2065(4)
3207(4)
3921(4)
3651(4)
2524(4)
593(3)
2758(3)
2287(3)
-796(3)
1671(4)
2698(4)
371(3)
529(3)
1663(4)
2185(3)
2167(3)
1023(3)
3227(3)
3548(3)
4564(3)
5269(3)
4987(3)
3949(3)
4918(3)
5788(3)
9484(5)
9785(6)
10807(6)
11012(6)
y
5970(3)
6271(3)
7585(3)
7093(3)
6723(3)
6866(3)
7359(3)
7707(3)
6198(4)
7517(4)
7933(3)
8385(3)
7359(3)
9087(3)
7901(4)
9957(3)
8687 (3)
8350(3)
8146(3)
8951(3)
9168(3)
9396(3)
5533(3)
5388(3)
4303(3)
4768(3)
2731(3)
4922(3)
4778(3)
3885(3)
3684(3)
3818(3)
4764(3)
4952(3)
6289(3)
5623(3)
5442(3)
5967(3)
6668(3)
6810(3)
4718(3)
7270(3)
3434(3)
4341(5)
4754(5)
5419(5)
z
U(eq)
2219(3)
1256(3)
3156(3)
3438(3)
4315(3)
4895(3)
4635(3)
3759(3)
4635(4)
5293(3)
-317(3)
-847(3)
-1458(3)
-1219(4)
-2990(3)
-1749(4)
-1223(3)
-1946(3)
-2194(3)
-2387(3)
-1588(3)
-1358(3)
2539(3)
2675(3)
2141(3)
3927(3)
3143(4)
4185(3)
3422(3)
3356(3)
3080(3)
3671(3)
3609(3)
3902(3)
571(3)
1155(3)
942(3)
125(3)
-464(3)
-232(3)
1597(3)
-1320(3)
1900(3)
814(5)
310(6)
-511(5)
30 (1)
31 (1)
22 (1)
26 (1)
34 (1)
36 (1)
28 (1)
24 (1)
53 (2)
39 (1)
27 (1)
29 (1)
28 (1)
41 (1)
50 (2)
46 (1)
28 (1)
35 (1)
31 (1)
36 (1)
29 (1)
33 (1)
24 (1)
23 (1)
27 (1)
29 (1)
48 (2)
33 (1)
24 (1)
28 (1)
29 (1)
28 (1)
25 (1)
22 (1)
22 (1)
22 (1)
21 (1)
24 (1)
23 (1)
23 (1)
29 (1)
31 (1)
116 (2)
70 (2)
72 (2)
67 (2)
Table 1.9.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 16. a
atom
C1(2)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
x
8700(3)
7690(10)
6721(11)
5741(15)
5772(16)
6701(12)
7586(10)
y
10480(3)
9726(8)
9819(8)
9427(12)
8791(12)
8810(8)
9281(8)
z
4073(2)
4383(8)
5046(8)
5228(12)
4684(13)
4172(9)
3892(8)
U(eq)
164(2)
127(4)
142(4)
210(7)
219(8)
140(4)
137(4)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.10. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A 2 x 103) for 17. a
atom
Cu(1)
Cu(2)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(1)
N(2)
N(101)
N(201)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
x
-257(1)
656(1)
236(1)
-385(1)
489(1)
-197(2)
-385(2)
-1823(1)
-1621(1)
-29(1)
1254(2)
1530(2)
-1120(2)
-810(1)
974(3)
1407(2)
1818(2)
2024(2)
1521(2)
1626(3)
-136(2)
-679(2)
-1484(2)
123(2)
-2117(2)
-458(4)
-301(2)
-982(2)
-1468(2)
-1282(2)
-636(2)
-139(2)
158(2)
-264(2)
-1150(2)
668(2)
-1464(2)
282(2)
196(2)
-436(2)
-903(2)
-587(2)
-30(2)
451(2)
-961(2)
-1087(2)
y
1625(1)
2275(1)
1646(1)
969(2)
2971(2)
2305(2)
2753(2)
1662(2)
3389(2)
4530(2)
2940(2)
1689(2)
2209(2)
3944(2)
3085(3)
3649(2)
2468(2)
2141(2)
949(2)
1619(3)
1127(2)
2200(2)
1606(2)
-82(2)
550(3)
1702(3)
609(2)
355(2)
907(2)
1113(3)
1487(2)
957(2)
2868(2)
4394(2)
3752(2)
3075(3)
4146(3)
5452(2)
3428(2)
3520(2)
4059(2)
4800(2)
4710(2)
4185(2)
3090(2)
3758(2)
z
U(eq)
6842(1)
7898(1)
9027(3)
7974(3)
6679(3)
5721(3)
10933(3)
8779(3)
6021(3)
7762(3)
8923(3)
7492(3)
9886(3)
6876(3)
9976(5)
8392(5)
9040(4)
7971(5)
7999(6)
6315(5)
8874(3)
10740(3)
9560(4)
9639(5)
10233(5)
12548(5)
9819(4)
9798(4)
10269(4)
11397(4)
11402(4)
10927(4)
5873(4)
6908(4)
5946(3)
4153(4)
4099(4)
6071(4)
4944(4)
4353(3)
4874(3)
5084(3)
5841(3)
5302(4)
8393(3)
7900(3)
43(1)
38(1)
44(1)
50(1)
44(1)
51(1)
50(1)
49(1)
51(1)
44(1)
44(1)
48(1)
35(1)
34(1)
66(1)
53(1)
49(1)
50(1)
68(2)
62(1)
38(1)
42(1)
40(1)
65(1)
66(2)
77(2)
46(1)
48(1)
48(1)
54(1)
52(1)
52(1)
39(1)
34(1)
37(1)
58(1)
58(1)
53(1)
43(1)
44(1)
43(1)
43(1)
40(1)
44(1)
34(1)
32(1)
Table 1.10.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 17.a
atom
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(13)
C(15)
C(16)
x
-1485(2)
-1740(2)
-1625(2)
-1233(2)
-1626(2)
-1904(2)
-1898(8)
-1622(6)
-1903(6)
-2509(6)
-2435(5)
-1586(7)
-2025(7)
-1812(6)
-1493(8)
-1490(4)
y
4275(2)
4094(2)
3429(2)
2920(2)
5003(2)
3268(3)
1055(9)
1604(6)
1568(7)
1216(7)
738(6)
-502(8)
-445(8)
-1162(8)
-1660(9)
-1307(5)
z
8395(3)
9379(3)
9896(3)
9366(3)
7860(4)
10986(4)
4271(16)
4966(12)
5992(13)
5845(12)
4908(10)
6540(14)
7500(13)
8151(14)
7219(17)
6345(8)
U(eq)
39(1)
39(1)
40(1)
33(1)
49(1)
55(1)
178(6)
129(4)
138(4)
140(4)
113(3)
192(6)
184(5)
189(5)
213(7)
108(3)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.11. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 21. a
atom
Cu (1)
0(101)
0(102)
0(201)
0(202)
0(103)
0(104)
0(203)
0(204)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(1D)
x
y
-455(1)
-1875(3)
-430(3)
-2152(3)
-380(3)
-1090(3)
2224(3)
2102(3)
-1414(3)
550(3)
341(3)
-1143(4)
-467(4)
1376(4)
-1902(4)
2447(4)
-1379(4)
-1071(4)
293(4)
1161(4)
561(4)
-702(4)
-1582(4)
-3276(5)
-4084(6)
-691(5)
-1496(5)
3393(5)
4692(5)
-1290(4)
-789(4)
1166(4)
-2090(5)
2073(4)
-1861(5)
-1278(4)
50(4)
836(4)
105(4)
-1126(4)
-1920(4)
-1636(6)
-2554(8)
-2086(7)
-2788(8)
-1261(17)
3253(1)
3557(2)
4159(2)
1915(2)
2353(2)
2713(2)
3631(2)
1286(2)
368(2)
3183(2)
823(2)
4120(2)
3293(3)
3805(3)
5534(3)
5109(3)
4116(3)
4863(2)
5162(2)
4672 (3)
4597(3)
4162(3)
4647 (3)
5315(3)
6001(4)
3731(3)
3783(4)
4804(4)
5204(4)
1839(3)
363(2)
867(2)
1365(3)
110(3)
-896(3)
1102(3)
868(3)
360(3)
-392(3)
-134(2)
364(3)
2084(4)
2336(6)
-1562(5)
-2291(5)
-1450(11)
z
5588(1)
6313(1)
5950(1)
5475(1)
5228(1)
7270(1)
6610(1)
5646(1)
6189(1)
6932(1)
5914(1)
6259(1)
7182(1)
6821(1)
6333 (2)
7058(2)
7769(1)
6573(1)
6664(1)
6995(1)
7425(1)
7346(1)
7008(1)
6215(2)
6010(3)
8167(2)
8557(2)
7420(2)
7401(2)
5243(1)
5886(2)
5586(1)
4503(2)
4980(2)
5600(2)
4925(1)
4821(1)
U(eq)
32(1)
41(1)
35(1)
49(1)
37(1)
35(1)
37(1)
35(1)
38(1)
28(1)
26(1)
29(1)
29(1)
30(1)
39(1)
45(1)
38(1)
33(1)
33(1)
33(1)
35(1)
33(1)
33(1)
52(1)
78(2)
48(1)
56(1)
55(1)
73(2)
32(1)
31(1)
28(1)
45(1)
38(1)
48(1)
33(1)
34(1)
5170(1)
31(1)
5288(2)
5466(1)
5115(2)
4260(2)
3868(2)
5281(3)
5439(3)
5855(6)
37(1)
31(1)
37(1)
64(2)
98(3)
48(2)
54(2)
62(5)
Table 1.11.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 21. a
atom
C(2D)
C(217)
C(218)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
Cu(2)
0(401)
0(402)
0(501)
0(502)
0(403)
0(404)
0(503)
0(504)
N(401)
N(501)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(413)
C(414)
C(415)
C(416)
C(417)
C(418)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
x
-2197(24)
2851(5)
4052(6)
385(3)
762(4)
1610(4)
2073(4)
1732(4)
881(4)
1994(5)
2272(5)
-1049(1)
-3104(3)
-1335(3)
-2424(3)
-644(3)
-3133(3)
706(3)
1391(3)
-2571(3)
-1214(3)
-545(3)
-2306(4)
-2408(4)
-281(3)
-2959(5)
696(4)
-3720(4)
-2411(4)
-1114(4)
-560(4)
-1508(4)
-2721(4)
-3288(4)
-4243(5)
-4668(7)
-3348(5)
-4452(6)
1375(5)
2762(5)
-1476(4)
-1680(4)
531(3)
-1569(4)
1942(4)
-2552(4)
y
-2290(17)
-546(3)
-752(5)
1986(2)
1211(2)
772(3)
1163 (3)
1937 (3)
2352(2)
-89(3)
2342(3)
-1895(1)
-1910(2)
-2561(2)
-644(2)
-1261(2)
-678(2)
-1679(2)
95(2)
1042(2)
-1188(2)
633(2)
-2428(2)
-1246(2)
-1795(3)
-3824(3)
-2877(3)
-1857(3)
-3026(2)
-3230(3)
-2567(3)
-2380(3)
-2044(2)
-2683(3)
-3761(3)
-4576(4)
-1284(3)
-1077(5)
-2292(4)
-2478(4)
-703(2)
979(2)
470(2)
-574(3)
1064(3)
2031(2)
z
U(eq)
5788(9)
5233(2)
5015(2)
6434(1)
6336(1)
6625(1)
7014(1)
7121(1)
6825(1)
6533(2)
7552(1)
9388(1)
8652(1)
8902(1)
9655(1)
9892(1)
7795(1)
8276(1)
9482(1)
9162(1)
8030(1)
9319(1)
8616(1)
7797(1)
8054(1)
8386(2)
7650(2)
7155(1)
8221(1)
8071(2)
7780(2)
7391(1)
7539(1)
7841(1)
8552(2)
8737(2)
6800(2)
6466(2)
7351(2)
7357(2)
9914(1)
9441(1)
9610(1)
10719(1)
10237(2)
9900(1)
97(8)
49(1)
70(2)
25(1)
28(1)
32(1)
33(1)
32(1)
27(1)
43(1)
42(1)
33(1)
36(1)
37(1)
39(1)
38(1)
33(1)
45(1)
34(1)
33(1)
25(1)
25(1)
30(1)
28(1)
30(1)
39(1)
45(1)
36(1)
31(1)
36(1)
34(1)
33(1)
28(1)
32(1)
50(1)
73(2)
49(1)
67(2)
58(1)
67(2)
27(1)
26(1)
26(1)
36(1)
36(1)
32(1)
Table 1.11.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 21. a
atom
C(507)
C(508)
C(509)
C(510)
C(511)
C(512)
C(513)
C(514)
C(515)
C(516)
C(517)
C(518)
C(601)
C(602)
C(603)
C(604)
C(605)
C(606)
C(607)
C(608)
N(1)
N(2)
N(3)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(9)
C(10)
C(11)
C(12)
C(13)
C(14)
C(15)
C(16)
C(17)
C(18)
x
-1242 (3)
149(4)
568(3)
-303(4)
-1653(3)
-2097(4)
-2888(4)
-3099(5)
-2251(5)
-3297(7)
2563(4)
3834(5)
-947(3)
-486(3)
63(4)
125(4)
-310(4)
-837(3)
570(4)
-229(5)
-4541(3)
-5894(3)
-4689(8)
-5273(4)
-4798(5)
-4528(4)
-5831(4)
-5181(4)
-4561(5)
-3163(4)
-2974(4)
-6915(4)
-6418(5)
-5230(5)
-6080(7)
-6568(4)
-5760(6)
-4875(4)
-5364(5)
-3861(7)
-2795(6)
y
z
-109(2)
10305(1)
155(3)
818(2)
1552(2)
1299(2)
649(2)
-932(3)
-1329(3)
2753(3)
3358(5)
1690(3)
1981(4)
-268(2)
457(2)
1041(2)
883(2)
164(2)
-410(2)
1837(3)
13(3)
2094(2)
-358(2)
2653(8)
1343 (3)
930(4)
2720(3)
3013(4)
2444(3)
3195(4)
1882(3)
10386(1)
10074(1)
10075(1)
9908(1)
10221(1)
10708(2)
11140(2)
9609(2)
9537(3)
9967(2)
10197(2)
8672(1)
8858(1)
8610(1)
8165(1)
7966(1)
8228(1)
8806(2)
7482(2)
6342(1)
8780(1)
7992(3)
6187(2)
5793(2)
5979(2)
5791(2)
6724(2)
6931(2)
6487(2)
1267(3)
6851(2)
-997(3)
-1876(4)
-434(4)
-352(6)
465(3)
1203(4)
-444(3)
-359(6)
2169(9)
1616(5)
8794(2)
8809(3)
8369(2)
7943 (2)
8797(2)
8791(3)
9168(1)
9610(2)
8032(3)
8089(2)
U(eq)
28(1)
31(1)
27(1)
28(1)
26(1)
28(1)
41(1)
54(1)
43(1)
102(3)
40(1)
54(1)
24(1)
24(1)
28(1)
30(1)
28(1)
25(1)
39(1)
42(1)
31(1)
32(1)
163(5)
44(1)
61(2)
39(1)
53(1)
39(1)
57(1)
34(1)
41(1)
47(1)
75(2)
52(1)
88(3)
40(1)
75(2)
39(1)
81(2)
130(5)
84(2)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
Table 1.12. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 22.a
atom
Cu(1)
Li(1)
0(1)
0(2)
0(101)
0(102)
0(201)
0(202)
0(103)
0(203)
0(104)
0(204)
N(101)
N(201)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
x
9329(1)
8580(4)
8034(2)
8372(2)
7423(2)
7778(2)
10311(2)
10873(2)
7523(2)
12658(2)
8469(2)
11647(2)
7983(2)
12115(2)
8631(5)
8958(6)
8898(5)
7902(4)
7176(4)
6835(4)
8011(6)
8932(4)
7119(2)
7155(2)
7676(3)
5022(3)
6155(4)
5072(3)
5844(2)
5826(3)
6312(3)
5605(3)
5791(3)
5343(3)
11074(2)
12264(2)
12827(2)
12232(3)
14859(3)
13707(3)
12353(2)
13330(2)
13823(2)
14287(2)
13249(2)
12716(3)
y
4813(1)
6815(4)
7282(2)
7960(2)
5270(2)
3782(2)
7279(2)
5977(2)
4948(2)
4967(2)
2060(2)
7785(2)
3508(2)
6383(2)
8534(4)
8584(5)
7308(4)
6566(4)
7984(5)
7570(4)
8014(7)
7943(5)
4202(2)
4011(2)
2403(2)
3379(3)
331(3)
3584(4)
3304(2)
2007(2)
1677(2)
1955(3)
3292(3)
3663(3)
7000(2)
7579(2)
6027(2)
8567(3)
6564(3)
9687(3)
7954(2)
7376(2)
7028(2)
8134(3)
8580(2)
8914(2)
z
U(eq)
9061(1)
8629(3)
9690(1)
7996(1)
8046(1)
8497(1)
8943(1)
9514(1)
5955(1)
8268(1)
6915(2)
7254(1)
6451(1)
7796(1)
10136(3)
11042(3)
11031(3)
10289(2)
7779(3)
6860(3)
6598(3)
7272(3)
8079(2)
6149(2)
6671(2)
8277(2)
6362(3)
5361(2)
7626(2)
7363(2)
6563(2)
5856(2)
6064(2)
6876(2)
9351(2)
7791(2)
8353(2)
10619(2)
9246(2)
8132(2)
9742(2)
9826(2)
9032(2)
8696(2)
8472(2)
9251(2)
28(1)
26(1)
40(1)
38(1)
33(1)
31(1)
27(1)
29(1)
35(1)
37(1)
45(1)
31(1)
24(1)
22(1)
59(1)
73(1)
66(1)
45(1)
65(1)
68(1)
80(2)
63(1)
25(1)
27(1)
29(1)
35(1)
50(1)
49(1)
25(1)
29(1)
32(1)
37(1)
32(1)
29(1)
22(1)
23(1)
26(1)
31(1)
39(1)
37(1)
23(1)
25(1)
26(1)
31(1)
26(1)
27(1)
Table 1.12.(con't) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 22.a
atom
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(ID)
C(2D)
C(3D)
C(4D)
C(5D)
C(6D)
C(7D)
C(8D)
x
10055(2)
11278(2)
11728(2)
10893(3)
9662(3)
9262(2)
13057(3)
8801(3)
11518(6)
11624(9)
12339(8)
12447(13)
12028(7)
11010(17)
11784(12)
11064(14)
y
4943(2)
5454(2)
5147(2)
4319(3)
3774(2)
4092(2)
5677(4)
2872(3)
12041(6)
11853(9)
11357(8)
11222(13)
10304(7)
10956(18)
10505(12)
10047(13)
z
7117(2)
7084(2)
6368(2)
5669(2)
5681(2)
6420(2)
6335(2)
4917(2)
6625(4)
5771(6)
6907(5)
5767(9)
6240(5)
6744(12)
5550(8)
6245(9)
U(eq)
22(1)
22(1)
27(1)
29(1)
27(1)
23(1)
38(1)
37(1)
102(2)
152(3)
70(2)
116(4)
59(2)
113(6)
68(3)
86(4)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
~
MeO 2C
CO 2Me
1. 3 LDA, toluene,
0 oC
2. 3 PhCH 2Br,
110 oC
0
MeO 2C
Ph
Ph
2. conc HC1
P
Ph
3
SOC12, A
OO
'ON
0
Cl
Ph
O
.O
O
py, DMAP (cat), A
N '
H2N1
,Ph
H3C
H 2BXDK (6)
Scheme 1.1.
r
Ph
Ph
O HO
OH O
PhC
1. KOH, EtOH/
THF, A
NH2
euCH
(0.5 equiv)
3
PhPh
Ph
5
5
Ph
Me 2N
O-Cu-O
1>9
j
0
V
O-Cu-OJ
ex.
Q
17-19
tmeda
[Cu(4,4'-Me 2bpy) 2] +
[Cu(XDK)]-
O - Cu- O
O,
f
/ ex.
2. vacuum
14a
O-Cu-O
or 2
n n= 1or
1A
ex.
RNC
NMe 2
-Cu- o
O
2 (4,4'-Me 2b PY)
20
NCCI3
CNR
NCCH3
I
E 4 NCN
2PPh3
CNR>14b
Cu
I
CNR
(Et4N)+[O- Cu- O
PPh 3
I
Cu
0
13
0
Cu
PPh 3
Scheme 1.2.
1PhLi
or
1 LiCN, TH
O
_O-Cu--O
OLi
OOn
>1
0
Figure 1.1. ORTEP (50% thermal ellipsoids) and space-filling diagrams of H 2 BXDK
(6).
Figure 1.2. ORTEP diagram of [Cu 2 (XDK)(MeCN)] (10) with 50% thermal ellipsoids.
0(201)
Figure 1.3. ORTEP diagrams with 50% thermal ellipsoids for (clockwise from top
left) [Cu 2 (XDK)(PPh 3 )2 ] (13), [Cu 2 (XDK)(2,6-Me 2 PhNC) 3 ] (14a), [Cu 2 (XDK)(g-2,6Me 2 PhNC)(2,6-Me 2 PhNC) 2 ] (14b), and [Cu 2 (XDK)(NB) 2 ] (15).
0(402)
Cu(3)
/
0(202)
Cu(1)
Figure 1.4. ORTEP diagrams with 50% thermal ellipsoids for (clockwise from top
left) [Cu 2 (XDK)]2 (16), [Cu 2 (XDK)(tmeda)] (17), (Et 4 N)[Cu(PXDK)] (21), and
[CuLi(XDK)(THF) 2 ] (22).
y = 2.1446 + 16.133x R= 0.99946
----
y= 1. 1984 + 14.333x K= 0.9999
-
y = 10. 364 + 16.345x R= 0.99581
ti.
_=L
+A-
ft01
Z%
+"
U
S---- ICu(Me2bpy)2)[Cu(XDK)
(20)
--- --- [Cu(MeCN)4(C104)
-+
.. .j
0.5
.
.
,
i
i
i
,
I
.
.
.
.
I.
- - (n-Bu4N)(PF6)
i
.
.
I
.
..
.
1.5
..
.
I
.
2.5
,
.
.
.
,
.
1
3.5
Concentration (mM)
Figure 1.5. Conductivity plots for 20, Bu4NPF6, and [Cu(MeCN) 4](C10 4 ) in CH 2C12 at
296 K.
Chapter II
Synthesis and Characterization of Cu(I)-Cu(II) Mixed-Valence and Cu(I)-M(II)
Heterodimetallic Bis(carboxylate-bridged) Complexes: Structural, Electrochemical,
and Spectroscopic Investigations
Introduction
The ubiquitous cellular respiratory protein cytochrome c oxidase (CcO)
couples the catalytic reduction of dioxygen to water with the production of a proton
electrochemical gradient across a cell membrane, providing the energy essential for
ATP synthesis from ADP and inorganic phosphate.' Another respiratory protein,
nitrous oxide reductase (N2 0R), plays an analogous role in denitrifying bacteria by
catalyzing the reduction of N 2 0 to N 2 and water. 2 A common feature of both of
these enzymes is their use of a unique electron transfer center, CuA. Recent
spectroscopic 3-8 and X-ray structural 9-11 studies have provided compelling evidence
that CuA is a fully delocalized mixed-valence "class III " 12 dicopper center. The X-ray
structural analyses revealed that each copper ion is ligated by two bridging thiolates
and a terminal histidine nitrogen, with weaker contacts occurring between a
methionine thioether and one copper and between a glutamate carboxylate oxygen
atom and the other (Table 2.1). Most remarkably, the CuA site possesses an intermetal distance of 2.5 A, which is consistent with the presence of a genuine metalmetal bond. This feature is unprecedented in biological systems and is undoubtedly
connected intimately with the highly unusual electronic properties and the function
of the center. 13
The recent identification of the CUA site has spawned interest in the
structural and spectroscopic properties of well-defined complexes to model its
electron transfer properties. Many mixed-valence dicopper complexes are known,
but most are fully localized class I systems, with no electronic exchange between the
d 9 and d10 metal centers. 12,14 A small number of class II dicopper complexes have
been characterized. 12,15-19 Some have been shown to exhibit temperature dependent
electronic exchange phenomena, whereby the unpaired electron becomes spintrapped upon cooling, as judged primarily by EPR spectroscopy.l1 -17 Fully
delocalized, type III mixed-valence copper complexes which remain delocalized at
liquid helium temperatures are rare.
The two types of class III dicopper complexes described to date employ a
tridentate N 2 S ligand, LiPrdacoS, 20,21 or octaazacryptand macrobicyclic ligands, L1-L3
(Table 2.1).22-24 In addition to having different bridging properties, the two ligands
afford complexes with very different Cu---Cu distances and metal ion geometries.
The N 2S ligand provides a Cu(1.5)Cu(1.5) complex of overall Ci-symmetry, each Cu
having a distorted trigonal pyramidal geometry. The Cu...Cu distance of 2.9306(9) A
is long and there is presumably no metal-metal bond. Ligands L1 -L3 afford D3dsymmetric complexes with trigonal bipyramidal Cu centers and Cu-Cu distances of
2.448(1), 2.415(1), and 2.419(1) A, respectively. The identical coordination
environments about the two copper ions within each complex suggest delocalized
mixed-valence formulations for all in the solid state. The delocalization origins of
these two classes of compounds is revealed by their frozen solution EPR (T = 4-20 K)
and electronic absorption spectral properties, summarized in Table 2.1. The N 2Sderived complex exhibits a rhombic EPR spectrum with a seven-line hyperfine
splitting of the two lower field components due to spin delocalization over both I =
3/2 Cu ions. In contrast, EPR spectra obtained for complexes with the
octazacryptands are axial and display seven-line hyperfine coupling on the lower
field, All component, indicating substantial dz2 character in the ground state. The
electronic absorption spectra of all these complexes exhibit relatively intense (E >
1000 M-lcm -1) features in the near-infrared (NIR) region, but the absorption maxima
differs substantially for the two different types of complexes, again suggesting
different electronic states.
Recently in two independent studies, 25-27 detailed descriptions of the
electronic structures of the CuA center and its models have been put forth based on
thorough analyses of UV-vis, NIR, MCD, EPR, EXAFS, and X-ray structural data,
coupled with molecular orbital calculations. The singly occupied molecular orbital
(SOMO) for the N2S-derived mixed-valence complex is partly composed of weakly
participating, n-bonding dx2-y2 metal orbitals. It is dominated by the antibonding
sulfur p-orbitals, however, as might be expected in this case since the Cu ions are too
far apart for direct d-orbital overlap. 25,26 At the other extreme, in the octazacryptand
systems the a* SOMO is dominated by dz2-dz2 out-of-phase overlap afforded by the
short metal-metal distance and lack of an efficient superexchange pathway through
the four-atom bridging groups. 26 The a* SOMO for CuA was assigned to be a
composite of those deduced for these two models, with significant metal dx2-y2-dx2y2 out-of-phase and sulfur p--px in-phase overlap. 25,26 Taken together, these studies
suggest that the superexchange pathway in this set of class III mixed-valence
complexes is comprised of overlap between metal d- or ligand p- orbitals, or both,
depending on the energetic accessibility of a metal-metal compared to a bridging
exchange pathway.
The above examples notwithstanding, the paucity of small molecule analogs
of the CuA center hampers efforts to develop general principles that govern the
assembly of dicopper mixed-valence cores and their class III behavior. For example it
would be of interest to know (1) what spectrum of ligands will assemble the mixedvalence
core
and
protect
it from
decomposition
pathways
such
as
disproportionation; (2) how the superexchange pathway is affected by Cu-Cu
distance, and number and donor properties of bridging ligands, metal ion
geometries, and the overall complex symmetry; and (3) how these properties affect
the ease with which the mixed-valence core can cycle reversibly between the
Cu(I)Cu(I) and Cu(1.5)Cu(1.5) oxidation states with minimal ligand reorganization
and at biologically relevant potentials. An efficient approach to exploring these
questions is to utilize a readily modified ligand system that will stabilize the
Cu(1.5)Cu(1.5) and Cu(I)Cu(I) units, while leaving open coordination sites for
docking ancillary ligands with variable donor properties to perturb incrementally
the overall electronic structure. This strategy will facilitate the construction of a
family of closely related complexes from which the relative importance of the above
factors can be evaluated.
In the present investigation, we have approached this goal by using the mxylylenediamine bis(Kemp's triacid imide) (H2XDK) ligand system, 28-30 previously
demonstrated to be an ideal platform for binding a variety of metal fragments with
labile coordination sites in both bioinorganic 2 9,3 1-37 and organometallic 3
8
applications. Previously we reported the synthesis and characterization of several
bis(carboxylate)-bridged dicopper(I) complexes derived from XDK and 7x-acceptor and
a-donor ligands. 28 In these complexes the copper atoms have linear two-coordinate,
trigonal three-coordinate, or pseudo four-coordinate geometries, and variable CuCu distances ranging from 2.5697(8) to 3.4211(6)
A.
Here we report a series of
dicopper mixed-valence complexes having variable ancillary ligands which facilitate
the analysis of the factors that influence their electronic behavior. The synthesis,
solid state and solution characterization, and electrochemical behavior of these
complexes and related Cu(I) heterodimetallic complexes are described, the latter
serving to enhance our understanding of the electronic properties of the mixedvalence system.
Experimental Section
General
Considerations. The complexes Cu 2 (XDK)(MeCN)
(1),
Cu 2 (PXDK)(MeCN) (2), and (Et 4 N)[Cu(PXDK)] (3) were prepared according to
literature procedures. 28 The compound [Fe(OTf) 2 (MeCN) 2] was prepared according
to a procedure used to obtain the Mn(II) analog. 39 All other reagents were procured
from commercial sources and used as received unless otherwise noted. THF,
benzene, toluene, pentane, and Et 2 0 were distilled from sodium benzophenone
ketyl under nitrogen. Dichloromethane and 1,2-dichloroethane were distilled from
CaH 2 under nitrogen. The NMR solvent C6 D 6 was degassed, passed through
activated basic alumina, and stored over 3 A molecular sieves prior to use. All air
sensitive manipulations were carried out either in a nitrogen filled Vacuum
Atmospheres drybox or by standard Schlenk line techniques at room temperature
unless otherwise noted.
Physical Measurements. NMR spectra were recorded on a Bruker AC-250 or
Varian XL-300 spectrometer.
1H
NMR chemical shifts are reported versus
tetramethylsilane and referenced to the residual solvent peak. FTIR spectra were
recorded on a BioRad FTS-135 FTIR spectrometer. UV-vis-NIR spectra were
recorded on a Cary 5E reference spectrophotometer. Conductivity measurements
were carried out in THF or CH 2C12 at 296 K with a Fisher Scientific conductivity
bridge, model 9-326, outfitted with a platinum black electrode. Elemental analyses
were performed by Microlytics, South Deerfield, MA.
Electrochemistry. Cyclic voltammetric measurements were carried out in a
Vacuum Atmospheres drybox under N 2 with an EG&G Model 263 potentiostat. A
three electrode configuration was used consisting of a 1.75 mm 2 platinum working
electrode, a Ag/AgNO3 (0.1 M in MeCN) reference electrode, and a coiled platinum
wire auxiliary electrode. A 0.5 M solution of Bu4 (NPF6 ), triply recrystallized from
acetone, was used as supporting electrolyte. Solute samples were typically 1-2 mM.
Scan rate profiles were conducted for each sample, at scan speeds of 50-500 mV/s,
and compared to that obtained for Cp2Fe under identical conditions. All cyclic
voltammograms were externally referenced to Cp2Fe, for which E1 / 2 = +143 mV in
THF (AEp = 68 mV, scan rate = 50 mV/s).
EPR Spectroscopy. For measurements at 9 K, data were collected on a Bruker
Model 300 ESP X-band spectrometer operating at 9.47 GHz. For measurements at 77
K, data were collected on a Varian E104 X-band spectrometer operating at 9.14 GHz.
The Q-band measurements were performed at 2K with a modified Varian E109
spectrometer operating at 35 GHz. Liquid helium temperatures were maintained
with an Oxford Instruments EPR 900 cryostat, and liquid nitrogen temperatures with
an EPR finger dewar. For all measurements 1 mM frozen solutions were prepared in
2-methyltetrahydrofuran, a solvent in which the samples glassed well. Solid
samples (-1 mg) were prepared as finely ground powders. Simulations were carried
out with the WINEPR SimFonia program package. 40 The fits incorporated coupling
of the unpaired spin simultaneously to each I = 3/2 copper center.
Extended Hiickel Molecular Orbital Calculations. These computations 41 were
carried out with the program YAeHMOP, 42 operating on a Silicon Graphics Indy
computer. Simplified models of the mixed-valence complexes 7 and 8 were
implemented, [Cu2(g-O2CCH3)2(OMe2)]+ and [Cu 2 (OH) 2 (OH 2 )(OMe2)4] + , and used
the core crystallographic coordinates determined for 8.
Preparation of Compounds. [Cu 2 (XDK)(k-OTf)(THF) 2] (4). To a stirred solution
of 1 (300 mg, 0.402 mmol) in THF (5 mL) was added a solution of AgOTf (105 mg,
0.402 mmol) in THF (1 mL) in one portion. The colorless solution immediately
turned dark purple and an off-white precipitate formed. The mixture was filtered
through Celite, and the filtrate was evaporated to dryness. Recrystallization from
THF/pentane at -30 oC provided 4 as thin purple blocks which appeared suitable for
X-ray crystallography (386 mg, 96%). IR (KBr) 2962, 2935, 2875, 1734, 1691, 1460, 1362,
1297, 1264, 1182, 1024, 868, 760, 637 cm-1; UV-vis (THF, Xmax, nm (,, M-1, cm-1)) 542
(1200), 768 (sh, 300), 956 (630). Anal. Calcd for C 45 H 6 2 N 2 0
14 Cu 2 F 3 S 1
(4. 1THF): C,
50.46; H, 5.83; N, 2.62. Found: C, 50.45; H, 6.08; N, 2.47.
[Cu 2 (PXDK)(g-OTf)(THF) 2] (5). Method A. This compound was prepared from
2 (50 mg, 0.055 mmol) and AgOTf (14 mg, 0.055 mmol) by an analogous procedure to
that used to prepare 4. Recrystallization from pentane and a trace amount of THF at
-30 'C afforded 5 as purple needles (29 mg, 45%).
Method B. To a stirred suspension of 3 (50 mg, 0.053 mmol) in THF (2 mL)
was added Cu(OTf)2 (19.6 mg, 0.053 mmol) in THF (1 mL) in one portion. Complex 3
was immediately consumed and the solution turned dark purple. After 15 min the
THF was removed in vacuo. The solid residue was taken up in Et 2 0 (2-3 mL) and
then filtered through Celite to remove the precipitated Et 4 N(OTf). Solvent removal
in vacuo followed by recrystallization provided 5 as purple needles. (25 mg, 40%). IR
(KBr) 2962, 2935, 2875, 1733, 1691, 1534, 1460, 1362, 1296, 1182, 1024, 868, 637 cm - 1 .
Anal. Calcd for C5 3 H 78 N 2 0
13 Cu 2 F 3 S 1 : C,
54.53; H, 6.73; N, 2.40. Found: C, 54.34; H,
6.54; N, 2.61.
[Cu 2 (XDK)(g-O 2 CCF3 )(THF) 2] (6). This compound was prepared from 1 (150
mg, 0.201 mmol) and AgO 2 CCF3 (44 mg, 0.20 mmol) by an analogous procedure to
that used to prepare 4. Recrystallization from THF/pentane provided 6 as purple
blocks which appeared suitable for X-ray crystallography (152 mg, 79%). IR (KBr)
2980, 2933, 2878, 1734, 1695, 1662, 1500, 1467, 1421, 1381, 1353, 1336, 1230, 1183, 1141,
1035, 838, 761, 667, 477 cm-1; UV-vis (THF, Xmax, nm (e, M -1 , cm-1)) 563 (2000), 806 (sh,
320), 942 (sh, 360), 1250 (500). Anal. Calcd for C4 2 H 54 N 2 0
12 Cu 2 F3 : C,
52.39; H, 5.65; N,
2.91. Found: C, 52.17; H, 5.63; N, 2.89.
[Cu 2 (XDK)(THF) 4](BF 4 ) (7). This compound was prepared from 1 (100 mg,
0.134 mmol) and AgBF 4 (26 mg, 0.13 mmol) by an analogous procedure to that used
to prepare 4. Recrystallization from THF/pentane provided 7 as purple plates (120
mg, 82%). IR (KBr) 2969, 2927, 2875, 1734, 1698, 1540, 1462, 1423, 1353, 1230, 1028, 957,
864, 759, 676, 523 cm-1; UV-vis (THF, Xmax, nm (e, M - 1, cm-1)) 536 (1600), 923 (1200).
Anal. Calcd for C4 8 H 70 N 2 0
12 Cu 2B 1 F4 : C,
51.29; H, 5.81; N, 2.99. Found: C, 50.98; H,
5.92; N, 3.04.
[Cu 2 (PXDK)(THF) 4 ](BF 4 ) (8). This compound was prepared from 2 (121 mg,
0.132 mmol) and AgBF 4 (26 mg, 0.132 mmol) by an analogous procedure to that used
to prepare 4.
Recrystallization from THF/pentane provided 8 as purple needles
which appeared suitable for X-ray crystallography (101 mg, 61%). IR (KBr) 2962, 2933,
2869, 1734, 1692, 1540, 1459, 1362, 1314, 1264, 1182, 1034, 866, 759, 673, 586 cm-1; UV-vis
(THF, Xmax, nm (,
C 60 H 94 N 2 0
M- 1 , cm-1)) 527 (1700),
12 Cu 2B 1F 4 : C,
878 (1200).
Anal. Calcd for
57.68; H, 7.58; N, 2.24. Found: C, 56.84; H, 7.25; N, 2.42.
[CuZn(PXDK)(OTf)(THF) 2 (H2 0)] (9). This compound was prepared from 3 (200
mg, 0.213 mmol) and Zn(OTf) 2 (94 mg, 0.21 mmol) by a procedure analogous to
method B used to prepare 5, except that the reaction mixture was allowed to stir for
12 h. Recrystallization from pentane with a trace of THF provided 9 as colorless
blocks which appeared suitable for X-ray crystallography. (154 mg, 61%). 1 H NMR
(300 MHz, C 6 D 6 , 296 K) 8 7.31 (1H, s), 6.63 (1H, s), 3.83 (8H, br s), 2.90-2.60 (4H, m),
2.30-1.92 (6H), 1.83 (6H, s), 1.68-1.03 (34H, m), 1.03-0.80 (16H, m), 0.75 (4H, d, J = 12.6
Hz); IR (KBr) 3451, 2963, 2933, 2874, 1734, 1676, 1577, 1459, 1365, 1309, 1184, 1027, 918,
761, 637 cm - 1 . Anal. Calcd for C 5 3 H 80 N 2 0
14 CulZn1
F3 S1 : C, 53.62; H, 6.79; N, 2.36.
Found: C, 54.22; H, 6.55; N, 2.34.
[CuFe(PXDK)(OTf)(NB)(MeCN)]2 (10a). To a stirred suspension of 3 (200 mg,
0.213 mmol) in THF (3 mL) was added [Fe(OTf) 2 (MeCN) 2 ] (106 mg, 0.243 mmol) in
THF (1 mL) in one portion. After 15 min the THF was removed in vacuo. The solid
residue was taken up in Et 2 0 (2-3 mL) and then filtered through Celite. Solvent
removal
in
vacuo
dichloroethane/norbornene
followed
by
recrystallization
from
1,2-
(NB, 1:1, v:w) and pentane afforded 10a as small
colorless blocks (146 mg, 60%) which appeared suitable for X-ray crystallography. IR
(KBr) 3049, 2871, 2742, 1737, 1699, 1594, 1502, 1412, 1368, 1315, 1181, 1033, 926, 862, 762,
637 cm - 1 . Anal. Calcd for C 54 H 75 N 3 011CuFeF 3 S1 : C, 56.47; H, 6.57; N, 3.65. Found:
C, 55.58; H, 6.80; N, 3.38. This sample was heated in vacuo at 90 oC for 6 h in an
attempt to remove completely the two lattice dichloroethane molecules, which were
identified by X-ray crystallography. Apparently only partial elimination was
achieved, and subsequent heating at higher temperatures resulted in decomposition
of the complex.
[CuZn(PXDK)(OTf)(NB)(H
2 0)]
(11). Compound 9 was prepared in situ from 3
(38 mg, 0.040 mmol) and Zn(OTf)2 (15 mg, 0.040 mmol) and then recrystallized from
benzene/norbornene (1:1, v:v) and pentane to afford 11 as colorless blocks which
appeared suitable for X-ray crystallography (27 mg, 57%). 1H NMR (250 MHz, C6 D6 ,
296 K) 8 7.35 (1H, s), 6.61 (1H, s), 5.22 (2H, s), 3.82 (4H, br s), 2.95-2.72 (6H, m), 2.30-1.90
(8H, m), 1.79 (6H, s), 1.68-0.60 (46H, m); IR (KBr) 3314, 2964, 2933, 2875, 1737, 1682,
1603, 1505, 1459, 1410, 1367, 1334, 1236, 1201, 1018, 926, 762, 637 cm-1. Anal. Calcd for
C52H 74N 20 12CulZn1 F3 S1 : C, 54.92; H, 6.55; N, 2.46. Found: C, 55.63; H, 6.78; N, 2.42.
Collection and Reduction of X-ray Data. All crystals were mounted on the tips
of quartz fibers with Paratone-N (Exxon), cooled to low temperature (~ -85 °C), and
placed on Siemens CCD X-ray diffraction system controlled by a Pentium-based PC
running the SMART software package. 43 The general procedures for data collection
and reduction follow those reported previously. 44 All structures were solved with
the direct methods programs SIR-92 45 or XS, part of the TEXSAN
46
and SHELXTL 47
program packages, respectively. Structure refinements were carried out with XL, part
of the SHELXTL program package. 47 All remaining non-hydrogen atoms were
located and their positions refined by a series of least-squares cycles and Fourier
syntheses. Hydrogen atoms were assigned idealized positions and given a thermal
parameter 1.2 times the thermal parameter of the carbon atom to which each was
attached. Empirical absorption corrections were calculated and applied for each
structure by using SADABS, part of the SHELXTL program package. 47
In the structure of 4, each coordinated THF molecule as well as one of the two
lattice THF molecules contain a carbon atom disordered over two positions. In each
case the atom was distributed over two positions and refined. In the structure of 6
each coordinated THF molecule was disordered over two positions. In one
molecule, two of the carbon atoms and the oxygen atom were refined at full
occupancy, and the occupancy of the remaining two carbon atoms was distributed
over two positions and refined. In the other, the occupancy of one carbon atom was
distributed over two positions and refined, and the remaining atoms were refined at
full occupancy. The lattice THF molecule in 6 contains large thermal parameters, so
each atom was refined at a site occupancy of 0.5. Two of the coordinated THF
molecules in the structure of 8 were disordered over two positions. Two of the
carbon atoms and the oxygen atom were refined at full occupancy, whereas the
remaining carbon atoms were distributed over two positions and refined. The
structure of 9 contains a coordinated THF molecule disordered over two positions,
and it was refined in similar fashion to those described for the structure of 4. Finally,
in the structure of 11 the copper atom and norbornene ligand are disordered. The
site occupancy of this fragment was distributed over two positions and refined. Bond
distances and angles for each orientation of 11 are reported in Table 2.3. For both
structures 9 and 11, the assignment of the metal atom positions as Cu or Zn was
based on chemically reasonable presumptions that (a) the overall neutral charge of
each complex necessitates the assignment of one mono- and divalent metal ion; (b)
the three-coordinate geometry for the metal coordinated to the norbornene ligand
in 11 is quite common for Cu(I) but not for Zn(II); and (c) the Cu-C distances in 11
are nearly identical to those observed for [Cu 2(XDK)(NB) 2]. 28
Important crystallographic information for each complex, including
refinement residuals, is available in Table 2.2. Selected bond distances and angles for
the coordination spheres of each structurally characterized complex are displayed in
Table 2.3, and final positional and equivalent isotropic displacement parameters are
listed in Tables 2.4-2.8.
Results and Discussion
Preparation and Structural Characterization of Mixed-Valence Complexes
[Cu 2 (XDK)(g-OTf)(THF) 2 ] (4), [Cu 2 (PXDK)(jg-OTf)(THF) 2 ] (5), [Cu 2 (XDK)(g0 2CCF3 )(THF) 2] (6), [Cu 2(XDK)(THF) 4](BF 4) (7), and [Cu 2 (PXDK)(THF) 4](BF 4 ) (8). Each
of these complexes was prepared by one electron oxidation of acetonitrile adducts 1
or 2 with the appropriate silver(I) salt in THF (Scheme 2.1). Removal of the
resulting solids followed by recrystallization afforded 4-8 as deep purple compounds
in moderate to excellent yield. Recovery of 5 and 8 was limited by their significant
solubility under the recrystallization conditions. The products appeared to be stable
in the presence of excess Ag + , suggesting that these mixed-valence complexes are
resistant to disproportionation followed by further Ag+ oxidation of the remaining
equivalent of Cu(I). By contrast, oxidation of 1 or 2 with Ag+ salts of more basic
anions, such as benzoate, led to mixtures of intractable blue-green products. This
result indicates that ancillary ligands more donating than trifluoroacetate are
incompatible with the dicopper-XDK mixed-valence framework. The triflate adduct
5 could also be prepared from mononuclear PXDK complex 3 and Cu(OTf) 2 . Because
of the propyl groups in PXDK, 5 is readily soluble in Et 20, allowing the Et 4N(OTf)
byproduct to be removed conveniently by filtration.
The IR spectra of compounds 4-8 display new features attributable to their
respective anions. In addition, the XDK carboxylate stretch in the dicopper(I) starting
materials 1 and 2 is shifted by 5-15 cm -1 to lower energy for each product, indicating a
change in Cu geometry. The UV-vis spectra of each product exhibit a relatively
sharp and intense (E = 1200-2000 M-l1cm -1) feature with a maximum at -545 nm
(Figures 2.1-2.3). For the three XDK complexes, this band is most intense for the
trifluoroacetate derivative. In the visible/near-infrared region, all the complexes
show broad absorptions between 700 and 1500 nm. Based on the peak shapes, this
feature appears to arise from a single transition for the BF4- complexes, but is made
up of overlapping components for the OTf- and 0 2CCF 3 - adducts. A similarly
intense (e > 500 M-l1cm -1) feature at low energy has been observed in other class II
and III mixed-valence copper complexes. In the class II systems it has been assigned
as an intervalence charge transfer, 16 ,1 7 and in the class III complexes as a Viy-*
transition within the Cu(1.5)Cu(1.5) manifold. 25,26 The relatively sharp transition
observed for the BF4- adduct parallels those observed for the class III octaazacryptand
complexes, 24,26 but the multiple bands appearing in the spectrum of the triflate and
0 2 CCF 3- derivatives are currently not understood. In the absence of additional
information such as MCD or single crystal data, we choose neither to assign the NIR
transitions nor make a definitive class II or III designation based on these spectra.
The solution stability of the mixed-valence complexes was assessed by UV-vis
spectroscopic and conductivity measurements. In all cases, the optical spectra
remained unchanged after standing in THF, benzene, or CH 2C12 for several days
under N 2 . Upon addition of a strongly coordinating solvent such as MeCN,
however, the solutions immediately turned pale blue-green and absorption spectra
typical of mononuclear Cu(II) were observed. The conductivity behavior of 4-8
similarly remained unchanged over the same time period in THF solution. The
triflate and 0 2CCF 3- adducts are non-electrolytes, whereas the BF 4 - adducts are 1:1
electrolytes as judged by a comparison of conductivity vs. concentration plots for 7
and Bu 4N(PF 6) (Figures 2.4 and 2.5). These results demonstrate that the [Cu 2 (XDK)]+
mixed-valence core is highly resistant to disproportionation, even in the absence of
excess THF, provided only weak field ligands are present.
The structures of 4, 6, and 8, as determined by X-ray crystallography, are
displayed in Figures 2.6-2.8. Selected bond distances and angles, atomic coordinates,
and equivalent isotropic displacement parameters are listed in Tables 2.3 and 2.4-2.8,
respectively. The structure of the triflate adduct 4 consists of two slightly distorted
square pyramidal copper atoms, each ligated by two XDK carboxylate oxygens, a THF
molecule, and an oxygen atom of a bridging triflate ion. The bond distances and
angles about each Cu atom are almost identical, and the dinuclear complex has
idealized C2v geometry, although no symmetry is crystallographically imposed on
the molecule. Both copper atoms are nestled slightly above (0.241(2) A) the rigidly
disposed and coplanar XDK carboxylate oxygen atoms, with nearly identical OXDKCu-OXDK angles. The fifth coordination site is filled by the adjacent copper
fragment, the Cu-Cu distance being 2.4093(8) A. This value is significantly smaller
than the 2.6287(5)
A
distance in the dicopper(I) in starting material 1 or in
homoleptic Cu 2(XDK), where the average Cu.-.Cu distance is 2.5901(9) A.28 The CuCu bond in 4 is slightly shorter than that observed for the octaazacryptand class III
mixed-valence complexes (Table 2.1).27 The longest Cu-O distance is that to the
triflate oxygen atom, which is -0.2
A longer
than the Cu-O bond involving THF,
which identifies the triflate as the axial ligand of the square pyramid. Because the
ligand fields presented by the three different type donor atoms, the carboxylates, THF
and copper, differ widely, the true symmetry at each metal center is rhombic, as
reflected by EPR spectroscopy (vide infra).
The solid state structure for trifluoroacetate analog 6 (Figure 2.7) is quite
similar to that of 4, with a few important distinctions. Firstly, the Cu-Cu bond in 6 is
2.3988(8) A, the shortest distance thus far observed for any dicopper mixed-valence
complex. Secondly, the axial Cu-O bonds to the trifluoroacetate ligand have
shortened by -0.1 A. Thirdly, the OXDK-Cu-OXDK angles have contracted by ~100,
reflecting displacement of the copper atoms by 0.363(3) A from the plane of the XDK
carboxylate oxygen atoms. In addition, the Cu-OXDK bond lengths are slightly longer
in 6 versus 4. All of these differences reflect the superior donor properties of the
trifluoroacetate ligand compared to the triflate, their relative pKa values being 0.348
and -5.9,49 respectively. Trifluoroacetate provides a greater share of the overall
electron density required by each copper ion, diminishing the bonding interaction to
the XDK carboxylate oxygens in 6. Overall the tris(carboxylate-bridged) motif
100
comprises a superior set of bridging ligands, however, a feature which accounts for
the slightly shorter Cu-Cu distance in 6 compared to 4.
In the structure of 8, the bridging anion has been displaced in favor of THF
ligands, due to the poor donor properties of the BF 4- anion and its even rarer
inclination to behave as a bridging ligand (Figure 2.8). Without the third bridge, the
Cu-Cu distance in 8 has lengthened slightly compared to that in 4. The axial CuOTHF bond lengths and the OXDK-Cu-OXDK angles are quite similar to the
analogous values in 4, however.
Preparation and Structural Characterization of Heterodimetallic Complexes
[CuZn(PXDK)(OTf)(THF) 2(H2 0)] (9), [CuFe(PXDK)(OTf)(NB)(MeCN)]
[CuZn(PXDK)(OTf)(NB)(H
2 0)]
2
(10a), and
(11). Heterodimetallic complexes containing Cu(I)
and divalent non-copper ions were sought to help delineate the significance of
metal-metal bonding in the dicopper mixed-valence derivatives. If the close contact
between copper atoms in the latter was only a consequence of the bridging XDK
ligand, then a similar metal...metal distance might be expected for analogous
Cu(I)M(II)(p-XDK) complexes. Although it is difficult to duplicate exactly the ligand
composition of the Cu(II) fragment in 4-8 to make such a comparison most relevant,
the successful preparation of triflate complex 5 from mononuclear 3 and Cu(OTf) 2 by
Method B (Experimental Section) suggested a route to the desired mixed-metal
complexes by substituting M(OTf) 2 starting materials for copper(II) triflate under
identical reaction conditions. Heterodimetallic Cu(I) complexes with Zn(II) and
Fe(II) were of particular interest because these occur in the copper-iron active site in
CcO' and the copper-zinc site in Cu, Zn superoxide dismutase.50 Although neither
active site complex involves carboxylate ligands, structurally characterized
Cu(I)Fe(II) and Cu(I)Zn(II) complexes are virtually nonexistent,5 1 so their structures
and reactivity are of intrinsic interest in the present context.
101
Exposure of 3 to a suspension of Zn(OTf) 2 in THF resulted in gradual
consumption of both reagents over 12 h (Scheme 2.1). As was the case for 5, the
purification of Cu(I)Zn(II) complex 9 was facilitated by its solubility in ether, which
allowed insoluble Et 4 N(OTf) to be filtered off. The analogous reaction with the XDK
analog of 3 yielded an identical product, as judged by 1 H NMR spectroscopy, but it
could not be separated from the byproduct salt. The water ligand in 9 might be
derived from a trace amount of water in the Zn(OTf) 2 reagent or the etheral
solvents; the synthesis proved to be quite reproducible, however.
The 1 H NMR spectrum of 9 displays a single set of XDK and THF resonances
in a 1:1 ratio. Some of the upfield XDK resonances corresponding to protons
adjacent to the metal binding sites, and the two THF resonances, were broadened at
room temperature. We ascribe this behavior to dynamic exchange process(es)
involving the THF ligand. A resonance that could be ascribed to water was
presumably obscured by the ligand resonances, but the identity of this ligand was
confirmed by X-ray crystallography, elemental analysis, and IR spectroscopy.
Complex 10a was prepared from 3 and [Fe(OTf) 2 (MeCN) 2 ] in a similar fashion.
The THF complex analogous to 9 did not afford crystalline material until excess
norbornene was added, which presumably displaces the THF ligand bound to
copper(I) in the precursor complex. A similar transformation was accomplished
with the Cu(I)Zn(II) complex by recrystallizing it in the presence of excess
norbornene to provide 11. Triflate complex 4 was unreactive toward excess
norbornene under similar conditions, as judged by UV-vis spectroscopy. This result
suggests that delocalization in this complex may mask any reactivity as a copper(I)
species, and that a Cu(1.5)Cu(1.5) oxidation state assignment is more appropriate for
4-8. Alternatively, kinetic factors may explain the inertness of 4 towards norbornene.
To elaborate further the chemistry of the Cu(I)Fe(II) system, attempts were
made to prepare an analog of the tris(carboxylate-bridged) complex 6. Compound 10a
102
was treated with 1 equivalent of Me4N[0 2C(4-tert-Bu-Ph)] in CH 2C12 , affording a
white solid presumed to be [CuFe(PXDK)(O2C(4-tert-Bu-Ph)(NB)(MeCN)]n(10b, n = 1
or 2), once extracted with Et 2 0 to remove the salt byproduct. Attempts to
recrystallize this complex for X-ray analysis were thwarted by its facile
disproportionation to Fe(III) products and copper metal upon standing in solution
for >2 h. The crude material was characterized by FTIR spectroscopy. A difference
spectrum of 10b and 10a is consistent with displacement of the triflate ligand by the
carboxylate (Figure 2.9). The increased basicity of the carboxylate compared to the
triflate ligand must render the iron(II) center more reducing, thus accounting for the
difference in stability of the two complexes.
The solid state structures of 9 and 11 are presented in Figures 2.10 and 2.11,
respectively. The structure of 9 consists of a trigonal copper atom ligated by a THF
and two carboxylate oxygen atoms. The zinc atom is trigonal bipyramidally
coordinated by five oxygen atoms contributed by two from PXDK, a monodentate,
terminal triflate, a THF, and a water molecule. The water is hydrogen bonded to the
imide carbonyls of the PXDK ligand, a common feature in XDK complexes when
water or alcohol ligands are present. 32-34,36 The triflate ligand displays no affinity for
Cu(I), and the metal-metal distance in this complex has lengthened to 2.8810(8)
compared to 2.4093(8)
A
A,
for the triflate analog 4. The X-ray structure of 11 is
somewhat analogous to that determined for 9 in that the copper atom is trigonal,
the triflate ligand is coordinated in the same fashion, and the metal ions are well
separated from one another. The copper-norbornene fragment is disordered over
two positions with equal site occupancies in each orientation. These two binding
modes were also observed within the same molecule of [Cu 2 (XDK)(NB) 2],28 and are
judged to be energetically similar.
The structure of 10a was of only modest quality, 52 but it served to identify the
overall geometry and is depicted in Scheme 2.1. The complex dimerizes in the solid
103
state via bridging triflate groups, the two halves of the dimer being related by a
center of inversion. Qualitatively, the Cu-Fe separation of 3.492(2) A is similar to
the Cu-Zn distances in 11. Thus replacement of the Cu(II) ion in 5 with Zn(II) or
Fe(II) provided complexes with reasonably similar composition but of different
structures, particularly with respect to the metal...metal separation. Collectively,
these structural and copper(I) ligand exchange studies lend credence to the
supposition that the short Cu-Cu distances and approximate C2v symmetry
observed for 4-8 are a consequence of metal-metal bonding and valence
delocalization, and not a function of the ligand architecture.
Electrochemical Properties of the Mixed-Valence Complexes. With the mixedvalence solvento complex 7 and the dicopper(I) analog 2 8 in hand, we were
interested to determine whether they could be electrochemically interconverted. It
was anticipated a priori that quasireversible behavior might be observed owing to
molecular reorganization, since the copper ion geometries in 7 and Cu 2 (XDK) differ
significantly. Moreover, it was of additional interest to determine whether the
reduction potential of the [Cu2(XDK)] + /Cu 2 (XDK) couple deviates significantly from
known trends for copper complexes because of the valence delocalized character of
the mixed-valence form.5 3
The homoleptic dicopper(I) complex exhibited a chemically reversible (ipa/ipc
~ 1) and electrochemically quasireversible (AEp = 105 mV, scan rate = 50 mV/s) cyclic
voltammogram, with E1/ 2 = -214 mV vs. Cp2Fe+/Cp2Fe (Figure 2.12). Plots of ipa and
ipc vs. the square root of the scan rate are linear (Figure 2.13), as would be expected
for a (nearly) reversible couple. The same electrochemical couple was observed for
the oxidized complex 7 (Figures 2.14 and 2.15: E1 / 2 = -222 mV, AEp = 132 mV, scan
rate = 50 mV/s, ipa/ipc - 1), confirming the one-electron nature of the process. An
identical couple was also observed for the triflate complex 4 (Figures 2.16 and 2.17:
E1/2 = -218 mV, AEp = 147 mV, scan rate = 50 mV/s, ipa/ipc ~ 1), suggesting that
104
triflate is dissociated upon dissolution in the electrolyte media, or upon reduction to
the Cu(I)Cu(I) species. At higher potentials an oxidation wave was detected, possibly
signaling formation of a Cu(II)Cu(II) species, with Epa = 443 mV (Figure 2.18). This
feature could not be made reversible, even at high scan speeds (> 500 mV/s). Unlike
the behavior noted for the more weakly coordinating triflate anion, the
trifluoroacetate ligand in 6 might remain associated with the Cu 2 (XDK)+ fragment
during cyclic voltammetry, because the analogous Cu(I)Cu(II)/Cu(I)Cu(I) reduction
wave is completely irreversible (Figure 2.19).
In order to place the electrochemical data presented in a more general context,
E1 / 2 values for a variety of Cu(I) and Cu(I)Cu(I) complexes are compiled in Table 2.9.
In each case the redox couple was chemically reversible and electrochemically
reversible, or nearly so (AEp < 150 mV). The mononuclear complexes listed contain
ligands ranging from a dianionic N2-bis(phenoxide) species (a) to neutral 54 or
cationic5 5 -5 7 donors with all nitrogen ligands (complexes d, g, h-j). For comparison
to the results obtained for 7, class I (e),58 II (b),1 7 and III (g) 2 3 mixed-valence systems
with well behaved electrochemistry were included. For c, the mixed-valence form
has not been isolated and characterized, but the dicopper(II) form undergoes two
sequential one-electron steps at the same potential.59 To make the comparison more
meaningful, potentials for each couple were referenced to the Cp2Fe+/Cp 2Fe couple
in THF. Scaling was accomplished with the aid of literature data relating SHE to
SCE, 60 AgCl/Ag to SCE,60 and SCE to Cp 2 Fe+/Cp 2 Fe (in THF) 61. These normalized
E1 / 2 values can be used as a rough approximation only, since the potentials for each
complex depend on experimental conditions, including choice of solvent, electrolyte
and electrolyte concentration, solvation, and ion pairing.
As expected from previous electrochemical studies of a large series of copper
complexes,5 3 the compounds in Table 2.9 display the general trend that more
negative reduction potentials occur as the ligand set becomes increasingly more
105
basic, with ligands which favor square planar or tetragonal over tetrahedral
geometries, and with decreasing positive charge on the complex. From this
standpoint all of the mixed-valence systems from the literature are unremarkable in
in the sense that their redox potentials are not anomalously affected by electronic
coupling between adjacent copper atoms, except for c. Given the tetraanionic charge
on the ligand and the rigidly planar structure of the dicopper(II) form, the E1 /2
values for this complex should more closely resemble that of a. Since little is known
about the electronic and solid state structures of the mixed-valence and dicopper(I)
forms of c, however, it is difficult to rationalize these findings.
For the Cu 2 (XDK)/Cu 2 (XDK) + couple, two competing factors unique to this
system can be identified which tend to shift the reduction potential in opposite
directions. One is the stability of the mixed-valence form due to its delocalized
electronic structure, and the other is the resistance of the dicopper(I) variant to
deviate from its linear, two-coordinate copper geometries. Judging from the large
positive deviation of the redox potential from its expected position in the series of
complexes (Table 2.9), the latter feature seems to predominate. Our previous studies
of ligand substitution reactions with the Cu 2 (XDK) scaffold revealed one of the
copper(I) ions to be unreactive towards a-donors. Even when exposed to excess
tetramethylethylenediamine
NCCH 3
I
Cu
(tmeda,
eq
1. tmeda (4 eq), THF
2. THF/pentane recrys.
1),
it preferred
to
retain
a
N
%/
OCu.o)
.
N
linear, two-coordinate "skewered" geometry. We suggest that the electrochemical
oxidation of Cu2(XDK) reaction involves coordination of two THF ligands to each
copper ion, thus making it more difficult to oxidize compared to the other copper
complexes with anionic oxygen donors which do not have the geometrical
106
constraints of XDK. In much the same way that ligands such as i and j prefer
copper(I) by favoring a tetrahedral geometry, the XDK ligand enforces a linear, twocoordinate copper(I) structure. The magnitude of the positive E1 / 2 shift appears to be
much greater for 7, however, since the all-oxygen Cu 2 (XDK) donor set should place
its Cu(I)Cu(II)/Cu(I)Cu(I) potential near those found for a-c.
It is interesting that the E1 / 2 value for Cu 2 (XDK) falls approximately in the
range found for blue copper proteins, ~ +200 to +800 mV vs. NHE, or ~ -600 to 0.0
mV vs. Cp2Fe+/Cp 2 Fe in THF, which employ a soft, monoanionic N 2 S2 ligand
donor set while imposing a geometry intermediate between square planar and
tetrahedral. Unlike our system, however, the rate of electron transfer is maximized
at these biological electron transfer centers by requiring minimal ligand
reorganization when cycling between the +1 and +2 oxidation states. Here we have
achieved biologically relevant redox potentials through geometric constraints, at the
cost of imparting a significant degree of reorganizational energy. Since these
properties could readily be achieved in a protein matrix, the carboxylate-bridged
dicopper(1.5) center would be a viable biological redox center.
EPR Studies of [Cu 2 (XDK)(THF)4 (BF4)] (7). EPR spectroscopy is a key tool for
characterizing electronic exchange in mixed-valence copper complexes because
seven-line hyperfine coupling of the unpaired electron to a pair of I = 3/2 copper
nuclei is diagnostic of spin delocalization. 15- 17, 20, 23 In class II systems, electron
exchange is typically mediated by population of vibrationally excited states, which
imparts sufficient kinetic energy for the electron to pass over the barrier separating
the electronic ground states of the two metal ions. Thus the rate of electron transfer
in these systems is temperature-dependent, and valence delocalization is observed
when the rate exceeds the time scale of the EPR experiment. In contrast, class III
mixed valence systems exhibit temperature independent delocalization behavior, at
least on the EPR time scale and over the temperature range to which the sample
107
may be cooled. In this case the electronic structure is best defined by a single
wavefunction encompassing both metal ions in which the unpaired electron
resides. EPR studies of the present system were therefore undertaken in both the
solid state and solution in order to probe the extent of electron delocalization, its
temperature dependence, and the similarities between structures in the two
different states.
A survey of the X-band frozen solution EPR spectra of 4, 6 and 7 obtained at
liquid helium temperature proved them to be quite similar, so a detailed
investigation was undertaken with the solvento adduct 7.62 EPR spectra for 7 are
presented in Figures 2.20 and 2.21 for frozen solution and powdered samples,
respectively, together with a simulation for each case, from which g values and
copper hyperfine coupling constants were derived. The spectra of 7 at 9 and 77 K
exhibited nearly identical rhombic signals with a readily discernible seven-line
copper hyperfine coupling pattern on the lowest field component and overlapping
hyperfine features on the two higher field components (Table 2.10). The X-band EPR
spectra of powdered samples acquired at the same temperatures were extremely
similar, albeit slightly broader, suggesting that the delocalized solid state structure is
retained in solution. A frozen solution Q-band spectrum acquired at 2 K also
exhibited seven distinct hyperfine lines on the lowest field component (Figure 2.22).
Furthermore, power dependence saturation studies on both the frozen solution and
powdered samples revealed that each spectrum corresponded to a single species.
Taken together, the EPR studies provide compelling evidence that the Cu 2 (XDK)+
mixed-valence series should be classified as a fully delocalized, class III system in
both the solid state and solution. Moreover, these studies represent the first report
of full delocalization for a dicopper mixed-valence species at 2 K, reinforcing its class
III designation.
108
The rhombic signal and distinct hyperfine coupling constants at each g value
were anticipated based on the approximate C2 v symmetry of the mixed-valence
complexes and the significantly different ligand fields presented by the three types of
ligands to each copper, the two carboxylate oxygens, the two THF oxygens, and the
adjacent copper fragment.63 The spectra may be compared with the rhombic spectra
obtained for the CUA site6 and for (CuLiPrdacS) 2+,20 each of which showed similar g
values to those obtained for 7, but the bis(g-thiolato) model complex exhibited
substantially smaller copper hyperfine coupling constants (Table 2.1). The larger
copper hyperfine interactions in 7 may be explained in part by a greater amount of
spin density residing at the metal centers because of the short Cu-Cu interaction and
the absence of a superexchange pathway through bridging ligands. In contrast to
these rhombic systems, the octazacryptand ligands afforded mixed-valence
complexes with axial EPR spectra arising from its trigonal ligand field.
Molecular Orbital Calculations. An extended Hiickel molecular orbital
treatment of 7 was undertaken to elucidate its frontier molecular orbitals. The
parameters of interest are the bonding and antibonding molecular orbitals
responsible for the Cu-Cu interactions, their relative energies, and their copper
orbital components. Net stabilization imparted to the dinuclear structure by Cu-Cu
bonding was assessed by analyzing the interaction of the two mononuclear
fragments as a function of Cu-Cu distance. Two simplified models were
implemented, [Cu 2(A-O2CCH 3)2(OMe 2)4 ] and [Cu2(OH) 2 (0H 2)2(OMe 2)4], each derived
from the crystallographic coordinates of the dicopper core in 8. The z-axis was taken
along the apical copper-OMe2 bond of one of the copper atoms, and the x- and y-axes
along the copper-copper and copper-carboxylate (hydroxide/water) oxygen vectors,
respectively.
Figures 2.23-2.24 display contour plots of the SOMO and second highest
occupied molecular orbital (SHOMO) for [Cu2(R-O2CCH 3 )2 (OMe 2)4 ]. The SOMO has
109
considerable Cu dx2-y2/Cu dx2-y2 a-antibonding character (-60% for each copper),
with a lobe from each metal pointed toward the other along the x-axis. The 4s (-11%
for each copper) and dz2 (-8%for each copper) orbitals also contribute significantly to
the SOMO, having the same phases as the dx2-y2 orbital on the two metals. In
addition, the p orbital contribution from each ligand is out-of-phase with respect to
the adjacent copper orbital lobe. The SHOMO in effect represents the bonding
counterpart of the anti-bonding SOMO, but has more dz2 (32%) and 4s (22%)
character at the expense of the dx2-y2 (36%). Again the ligand p orbitals are out-ofphase with respect to the adjacent copper orbital lobe, and in neither the SOMO nor
the SHOMO are the carboxylate carbon atoms participating. An exchange pathway
for electron delocalization therefore appears to be accessible only through the Cu-Cu
interaction and not through the carboxylate ligands. Additional support for a net
Cu-Cu bonding interaction is obtained from a reduced Mulliken overlap
population analysis, which revealed that the overall Cu-Cu overlap population to
be +0.1495 at the crystallographic Cu-Cu distance of 2.40
A. This
value may be
compared to the average overlap population of +0.5362 for C-O single bonds in the
same structure. Hence the short Cu-Cu distance in the mixed-valence complexes is
indicative of a weak metal-metal bond.
A fragment molecular orbital (FMO) analysis was carried out on
[Cu 2 (OH)2 (OH 2)2 (OMe 2)4 ], a simpler model which permits the two copper fragments
to be separated without breaking any carbon-oxygen bonds (Figure 2.25). The
frontier molecular orbitals for this model had essentially identical energies and
orbital contributions as those obtained for [Cu2(9-O2CCH 3 )2 (OMe 2 )4 ]. The FMO
analysis revealed that a significant bonding/antibonding interaction results between
the highest occupied molecular orbital (HOMO) of the Cu(I) and Cu(II) fragments
when the two are brought together. This interaction is also observed in a Walsh
diagram, where the molecular orbital energy is plotted as a function of the Cu-Cu
110
distance (Figure 2.25). The orbitals perturbed most dramatically are the SHOMO and
SOMO, those suspected to play the greatest role in Cu-Cu bonding. The energy gap
between the SOMO and SHOMO of [Cu 2 (OH) 2(OH 2 )2(OMe 2)4 ] is maximized at -2.2
A,
reasonably close to the crystallographically determined distance of 2.40
A.
A
minimum for the total energy of the molecular orbitals is reached at a Cu-Cu
distance of -2.9
A.
Greater error for this latter parameter is to be expected, since the
total energy is made up of the individual energies of the 65 occupied molecular
orbitals. Nevertheless, both the FMO and Walsh analyses support the idea that net
stabilization is imparted to these mixed-valence complexes through Cu-Cu
bonding. Furthermore, the bonding interaction principally utilizes the Cu dx2-y2
orbitals. This outcome does not support a previous assertion that strong Cu-Cu
bonding can only be mediated by Cu dz2/Cu dz2 overlap, and that (dx2_y2) 1 dimers
are always held together exclusively as a consequence of their ligand structures. 22
Instead, we conclude that the only strict requirement for Cu-Cu bonding in these
dimers is reasonable a-type overlap between two adjacent metal orbitals and,
depending on the geometry, this interaction can be achieved with dx2-y2 orbitals.
Conclusions
A series of dicopper mixed-valence complexes have been assembled with the
XDK ligand system. Their fully delocalized, class III behavior has been demonstrated
experimentally through (a) X-ray crystallographic studies which show that the
coordination environments about each copper atom are identical, and (b) solid state
and solution EPR studies which demonstrate that the unpaired spin is coupled
simultaneously to both I = 3/2 copper ions down to 2 K. Support for a stabilizing
Cu-Cu bonding interaction in these complexes was provided by (a) the synthesis of
Cu(I) heterodimetallic complexes with other divalent metal ions which are of
similar composition but have much longer Cu(I).--..M(II) distances; (b) the lack of
111
reactivity of the mixed-valence
complexes with norbornene, which reacts
quantitatively with the Cu(I) fragment of the heterodimetallic complexes; and (c)
extended HUickel molecular orbital calculations, which show a Cu-Cu interaction in
the SOMO and SHOMO that is composed primarily of Cu dx2-y2/Cu dx2-y2 orbital
overlap. Cyclic voltammetric studies revealed an electrochemically quasireversible
Cu(I)Cu(II)/Cu(II)Cu(II) wave with a very positive E 1 / 2 value, tentatively attributed
to the geometrical constraints imposed by the XDK ligand, which favors the linear
two-coordinate Cu(I) geometry. In the aggregate, these studies significantly enhance
our understanding of the assembly, stability, and electronic structure of class III
mixed-valence Cu-Cu bonded systems. We suggest that this new structural and
redox active motif would serve well as a biological electron transfer center in
carboxylate-bridged environments.
Acknowledgement. This work was supported by grants from the National
Science Foundation and AKZO Corp.
112
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114
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Tanase, T.; Lippard, S. J. Inorg. Chem. 1995, 34, 4682-4690.
(34)
Yun, J. W.; Tanase, T.; Pence, L. E.; Lippard, S. J. J. Am. Chem. Soc. 1995, 117,
4407-4408.
(35)
Tanase, T.; Yun, J. W.; Lippard, S. J. Inorg. Chem. 1995, 34, 4220-4229.
(36)
Watton, S. P.; Masschelein, A.; J. Rebek, J., Jr.; Lippard, S. J. J. Am. Chem. Soc.
1994, 116, 5196-5205.
(37)
Goldberg, G. P.; Watton, S. P.; Masschelein, A.; Wimmer, L.; Lippard, S. J. J.
Am. Chem. Soc. 1993, 115, 5346-5347.
(38)
Steinhuebel, D. P.; Lippard, S. J. Inorg. Chim. Acta 1998, In Press,
(39)
Bryan, P. S.; Dabrowiak, J. C. Inorg. Chem. 1975, 14, 296.
(40)
WINEPR-SimFonia. 1.25; Bruker Analytik GmbH: Karlsruhe, FRG, 1994-1996.
(41)
Hoffmann, R. J. Chem. Phys. 1963, 39, 1397-1412.
115
(42)
Landrum, G. A. YAeHMOP: Yet Another extended Huckel Molecular Orbital
Package. 2.0; Cornell University: Ithaca, NY, 1995. YAeHMOP is freely
available on the WWW at URL.
(43)
SMART. 4.0; Siemens Industrial Automation, Inc.: Madison, WI, 1994.
(44)
Feig, A. L.; Bautista, M. T.; Lippard, S. J. Inorg. Chem. 1996, 35, 6892-6898.
(45)
Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Polidori, G.; Spagna,
R.; Viterbo, D. J. Appl. Crystallogr.1989, 22, 389-393.
(46)
TEXSAN: Single Crystal Structure Analysis Software. 1.6c; Molecular
Structure Corporation: The Woodlands, TX, 1995.
(47)
SHELXTL: Structure Analysis Program.5.0; Siemens Industrial Automation,
Inc.: Madison, WI, 1995.
(48)
The Merck Index, Twelth Edition S. Budavari, Ed.; Merck Research
Laboratories: Whitehouse Station, NJ, 1996.
(49)
Guthrie, J. P. Can. J. Chem. 1978, 56, 2342-2354.
(50)
Valentine, J. S.; Pantoliano, M. W. In Copper Proteins; T. G. Spiro, Ed.; Wiley:
New York, 1981.
(51)
(a) A Cambridge Structural Data Base (CSD) search yielded only Cu(I)Fe(II)
complexes with ferrocenyl-phosphine ligands (See, for example: Neo, S. P.;
Zhou, Z-Y.; Mak, T. C. W.; Hor, T. S. A. J. Chem. Soc. Dalton Trans. 1994, 34513457). A Cu(I)Fe(II) trihydride bridged species was also reported, Van Der
Sluys, L. S.; Miller, M. M.; Kubas, G. J.; Caulton, K.G. J. Am. Chem. Soc. 1991,
113, 2513-2520. (b) The only structurally characterized Cu(I)Zn(II) complex
reported to date (CSD search) is a nitrite-bridged compound. See: Halfen, J. A.;
Mahapatra, S.; Wilkinson, E. C.; Gengenbach, A. J.; Young, V.G., Jr.; Que, L.,
Jr.; Tolman, W. B. J. Am. Chem. Soc. 1996, 118, 763-776.
(52)
X-ray data for 10a from dichloroethane/pentane: P2/n, a = 19.0883(5), b =
14.5289(3), c = 23.4342(6), P = 109.1900(10), V = 6137.9(3), Z = 4, T = 188 K, R =
116
14.12%, wR 2 = 40.36. This structure was not fully refined due to major
disorder of the two lattice dichloroethane molecules.
(53)
Patterson, G. S.; Holm, R. H. Bioinorg. Chem. 1975, 4, 257-275.
(54)
Tolman, W. B. Inorg. Chem. 1991, 30, 4877-4880.
(55)
Wei, N.; Murthy, N. N.; Tyeklar, Z.; Karlin, K. D. Inorg. Chem. 1994, 33, 11771183.
(56)
Mahapatra, S.; Halfen, J. A.; Wilkinson, E. C.; Pan, G.; Wang, X.; Young, V.G.,
Jr.; Cramer, C. J.; Que, L., Jr.; Tolman, W. B. J. Am. Chem. Soc. 1996, 118, 1155511574.
(57)
Sorrell, T. N.; Jameson, D. L. Inorg. Chem. 1982, 21, 1014-1019.
(58)
Mahroof-Tahir, M.; Karlin, K. D. J. Am. Chem. Soc. 1992, 114, 7599-7601.
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Fenton, D. E.; Schroeder, R. R.; Lintvedt, R. L. J. Am. Chem. Soc. 1978, 100,
1931-1932.
(60)
Bard, A. J.; Faulkner, L. R. In Electrochemical Methods Fundamentals and
Applications John Wiley & Sons: New York, 1980.
(61)
Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877-910.
(62)
The detailed EPR analyses were carried out in collaboration with Dr.
Roman Davydov of Northwestern University.
(63)
Hathaway, B. J.; Billing, D. E. Coord. Chem. Rev. 1970, 5, 143-207.
117
Table 2.1. Summary of pertinent spectroscopic and structural data on known class III
mixed-valence copper systems.
Complex
Cys
His
Visible-NIR (Xmax, nm
Cu-Cu
(E, M -1 , cm- 1))
Dist.(A)
363 (120 0 ),a 480 (3000),
2.5-2.7
532 (3000), 808 (1600)
M-Cu
N-..
Cu-N
s
,"
ref.
gmin = 2 .003,Cgmid = 2.005,
6,7,
gmax = 2.203,
9-11
Ax6 5- Cu = 105 G,
c
Me
EPRb
Ay65-Cu = 116 G,
His
Cys
Az65 -Cu = 235 G
CuA
7)+
358 (2700), 602 (800),
2.9306(9)
gl = 2.010, g2 = 2.046,
g3 = 2.204, A 2Cu = 36.3 G,
786 (sh), 1466 (1200)
A3 Cu = 49.9 G
(CuLiPrdacoS) 2 (OTf)
73+
600-650 (1500-3500),d
2.448 e
22-23
A41 = 11 G, A± = 111 G
756 (5000)
N-Cu- --Cu-N
g I= 2.004, gj = 2.148,
1 3+
(Cu 2 L )
H 73+
H
622 (2900), 736 (4500)
2.415(1)
g 11= 2.02, g± = 2.15,
24
Ai = 22 G, A± = 115 G
N-Cu---Cu-N
H
2 3+
(Cu 2 L )
N
\
1
S3+
3 3+
600-650 (1500-3500),d
750-780 (5000)
2.419(1)
g = 2.00, g± = 2.17,
22, 27
A = 11 G, AL = 92 G
(Cu 2 L )
aFrom Paracoccus denitrificansCcO (see ref. 7). bAll parameters were derived from simulated spectra.
c65Cu- and [15N]Histidine-Enriched N20R from P. stutzeri (see ref. 6). dOnly ranges were reported for
the absorption maxima and molar absorptivities. eNo esd reported.
Table 2.2. Summary of X-ray Crystallographic Data.
formula
fw
space group
a,
b,A
c, A
3, deg
V, A 3
Z
Pcalcd, g /cm 3
T, oC
g(Mo Ko), mm - 1
transmission coeff
20 limits, deg
total no. of data
no. of unique data
observed dataa
no. of parameters
R(%)b
wR 2(%)c
max, min peaks, e/A
3
4.2THF
6.0.5THF
8.1THF
9.0.5THF
11
C49H70N2015
Cu 2 S 1F 3
1143.21
P21/n
20.203(2)
12.0901(10)
22.130(2)
94.522(5)
5388.6(8)
4
1.409
-85
0.904
0.817-1.000
3-46
20000
7456
5684
624
5.19
12.59
0.533, -0.378
C 4 4 H 5 8 N 2 0 1 2 .5
Cu 2F 3
4977.49(6)
P21 21 2 1
11.02460(10)
16.31380(10)
27.67530(10)
C64H102N2013
Cu 2B 1F 4
1321.37
P21/n
17.4237(9)
21.5206(12)
18.8570(10)
105.9970(10)
6797.0(6)
4
1.291
-85
0.696
0.806-1.000
3-46
25459
9533
6996
748
8.50
18.14
1.112, -0.448
C55H84N2014.5
CulZnlF 3 S 1
1223.21
C2/c
25.0154(5)
18.2877(2)
25.9855(5)
92.1000(10)
11879.7(4)
4
1.368
-85
0.870
0.885-1.000
3-57
33683
13213
8258
686
6.75
16.37
0.984, -0.613
C52H74N2012
CulZnlF 3S 1
1137.10
P21/n
15.5186(2)
24.28620(10)
15.93940(10)
113.3850(10)
5513.91(8)
2
1.370
-85
0.929
0.718-1.000
3-57
31387
12392
7881
704
7.09
17.60
0.792, -0.753
aObservation criterion: I > 2a(I). b R =
4977.49(6)
4
1.333
-85
0.924
0.668-1.000
3-46
19795
7086
6246
559
4.71
12.45
0.744, -0.380
I IFo I - IFc I I /II Fo I . CwR 2 = {[w(Fo2 -FC2 )2 ]/l[w(Fo2 )2 ]}1 / 2 .
119
Table 2.3. Selected Bond Distances and Angles.a
Distances (A)
Angles (deg)
Cul-Cu2
2.4093(8)
0102-Cul-0202
164.6(2)
Cul-0102
1.873(3)
0102-Cul-0401
Cul-0202
0401-Cul-0502
Cul-0401
1.873(3)
2.315(4)
96.4(2)
98.28(3)
Cul-0502
Cu2-0101
Cu2-0201
164.03(14)
2.060(3)
0101-Cu2-0201
0101-Cu2-0402
0402-Cu2-0501
Cul-Cu2-0402
Cu2-Cul-0401
91.82(13)
92.27(10)
Cu2-0402
1.891(3)
1.887(3)
2.242(3)
Cu2-0501
2.052(3)
Cul-Cu2
2.3988(8)
0102-Cul-0202
157.9(2)
Cul-0102
1.910(4)
0102-Cul-0401
99.9(2)
Cul-0202
Cul-0401
Cul-0502
1.908(4)
2.150(4)
0401-Cul-0502
0101-Cu2-0201
97.5(2)
2.050(4)
0101-Cu2-0402
Cu2-0101
Cu2-0201
0402-Cu2-0501
Cul-Cu2-0402
Cu2-0402
1.891(3)
1.889(3)
2.166(4)
105.8(2)
97.7(2)
87.03(12)
Cu2-Cul-0401
88.27(13)
Cu2-0501
2.083(3)
Cul-Cu2
Cul-0102
Cul-0202
Cul-0401
Cul-0402
2.4246(12)
165.4(2)
102.6(2)
2.087(5)
0102-Cul-0202
0102-Cul-0401
0401-Cul-0402
0101-Cu2-0201
0101-Cu2-0501
Cu2-0101
1.883(5)
0501-Cu2-0502
Cu2-0201
1.881(5)
Cul-Cu2-0501
90.3(2)
101.26(14)
Cu2-0501
2.270(5)
Cu2-Cul-0401
102.7(2)
Cu2-0502
2.042(5)
1.885(4)
1.883(4)
2.285(5)
100.26(14)
87.94(10)
156.6(2)
89.6(2)
166.3(2)
91.8(2)
120
Table 2.3. (cont.) Selected Bond Distances and Angles.a
Distances
Angles
Cul...Zn1
2.8810(8)
0102-Cul-0202
Cul-0102
0102-Cul-0401
Cul-0202
1.891(3)
1.890(3)
Cul-0401
2.228(3)
0101-Znl-0201
93.52(13)
150.03(13)
Znl-0101
1.930(3)
0101-Znl-0501
92.71(14)
Znl-0201
1.938(3)
2.145(3)
0501-Znl-0504
90.45(14)
0501-Znl-0505
178.64(13)
Znl-0501
0202-Cul-0401
162.44(14)
102.40(12)
Znl-0504
Znl-0505
2.025(3)
Cul-..Znl
Cul'...Zn1
3.732(2)
0102-Cul-0202
109.84(14)
3.294(2)
0102-Cul'-0202
107.0(2)
Cul-0102
1.981(3)
0102-Cul-C401
104.3(4)
Cul-0202
1.973(3)
105.2(4)
Cul-C401
Cul-C402
2.044(14)
0102-Cul'-C41
0101-Znl-0201
99.57(14)
Cul'-0102
Cul'-0202
1.998(3)
0101-Znl-0501
0101-Znl-0504
2.027(3)
0201-Znl-0501
106.85(14)
Cul'-C41
2.024(12)
0201-Znl-0504
105.59(12)
Cul'-C42
Znl-0101
Znl-0201
Znl-0501
Zn1-0504
2.004(11)
1.911(3)
1.917(3)
2.021(3)
1.970(3)
2.189(3)
2.12(2)
132.26(13)
103.15(12)
aNumbers in parentheses are estimated standard deviations of the last significant
figure. Atoms are labeled as indicated in Figures 2.6-2.10.
121
Table 2.4. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 4. a
atom
Cu(2)
Cu(1)
S(401)
F(401)
F(402)
F(403)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(403)
0(501)
0(502)
0(601)
0(602)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
x
2(1)
528(1)
1166(1)
1462(2)
1028(3)
423(2)
-716(2)
-215(2)
-2058(2)
-1017(2)
624(2)
1104(2)
649(2)
-243(2)
1128(2)
619(2)
1807(2)
-465(2)
911(2)
-2975(4)
-2851(4)
-1529(2)
209(2)
-687(2)
-1968(2)
-1390(2)
-1001(3)
-1829(3)
-2990(2)
-1246(2)
-1337(2)
-1741(2)
-2413(2)
-2318(2)
-1905(2)
1061(2)
242(3)
741(2)
2168(3)
1768(3)
767(3)
1594(2)
1838(2)
1404(2)
1276(3)
913(2)
y
4179(1)
5131(1)
5773(1)
7814(3)
6877(4)
7462(3)
5177(3)
6063(3)
3708(3)
5338(3)
3035(3)
3921(3)
2489(3)
829(3)
6126(3)
5076(3)
5431(3)
3271(3)
5846(3)
5271(6)
606(7)
4545(3)
1672(3)
5941(4)
4551(4)
5458(4)
7716(4)
7179(5)
5396(4)
6798(4)
7272(4)
6550(4)
6286(4)
5645(4)
6347(4)
3117(4)
982(4)
1892(4)
2690(5)
1160(5)
-689(4)
2222(4)
2059(4)
1331(4)
229(4)
413(4)
z
2107(1)
2973(1)
1688(1)
1431(2)
679(2)
1359(2)
2135(1)
2927(2)
2509(2)
4162(2)
2278(2)
3083(2)
4339(2)
2630(2)
2309(2)
1466(2)
1537(2)
1414(2)
3770(2)
5015(3)
4693(4)
3324(2)
3476(2)
2528(2)
2801(2)
3713(2)
2090(3)
4137(2)
2290(3)
2504(2)
3134(2)
3546(2)
3210(2)
2634(2)
2217(2)
2718(2)
2969(2)
3917(2)
2436(3)
4461(3)
2557(3)
2791(2)
3459(2)
3835(2)
3513(2)
2890(2)
U(eq)
30(1)
32(1)
45(1)
76(1)
104(2)
96(1)
34(1)
38(1)
38(1)
46(1)
38(1)
39(1)
49(1)
46(1)
61(1)
53(1)
72(1)
43(1)
38(1)
139(3)
157(3)
27(1)
31(1)
32(1)
30(1)
33(1)
45(1)
52(2)
45(1)
33(1)
36(1)
36(1)
38(1)
33(1)
33(1)
35(1)
37(1)
35(1)
53(2)
54(2)
53(2)
39(1)
41(1)
39(1)
43(1)
38(1)
122
Table 2.4.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 4.a
atom
C(212)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(501)
C(502)
C(50D)
C(503)
C(504)
C(505)
C(506)
C(507)
C(51D)
C(508)
C(601)
C(602)
C(603)
C(604)
C(605)
C(606)
C(607)
C(60D)
C(608)
x
1352 (2)
-664 (2)
-440 (2)
-834 (2)
-1450 (2)
-1686 (2)
-1286 (2)
-602 (3)
-2345 (2)
1012 (3)
-62 (3)
-387 (8)
-217 (6)
-963 (4)
-996 (3)
640 (3)
546 (4)
541 (9)
974 (9)
973 (4)
-2525 (6)
-2689 (5)
-3380 (6)
-3548 (5)
-3367 (6)
-4020 (6)
-3832 (10)
-3808 (16)
-3116 (6)
y
1121
3095
2065
1398
1807
2832
3469
256
3250
7036
2737
1765
1449
1524
2528
5431
6422
7380
7362
7056
5435
4730
4355
4709
-155
472
1603
1103
1205
z
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(4)
(5)
(6)
(14)
(10)
(7)
(5)
(5)
(5)
(11)
(11)
(4)
(10)
(9)
(10)
(9)
(10)
(11)
(27)
(35)
(10)
2503
3404
3610
3946
4079
3888
3540
4157
4061
1268
972
750
1066
1152
1562
4320
4721
4332
4442
3799
5517
6029
5848
5192
4476
4575
4865
5066
5202
U(eq)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(2)
(3)
(3)
(10)
(7)
(4)
(6)
40(1)
29(1)
29(1)
33(1)
32(1)
30(1)
28(1)
51(1)
42(1)
61(2)
67(2)
63(6)
56(5)
115(4)
56(2)
51(1)
75(2)
59(6)
64(6)
62(2)
133(4)
126(4)
139(4)
123(3)
139(4)
(6)
151(4)
(12)
(17)
(6)
180(8)
50(19)
140(4)
(3)
(2)
(3)
(6)
(6)
(3)
(6)
(5)
(5)
(5)
in parentheses are estimated standard deviations of the
last significant figure. bU(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
123
Table 2.5. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 6. a
atom
Cu(1)
Cu(2)
F(401)
F(402)
F(403)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
x
-6207(1)
-7309(1)
-8136(7)
-9671(6)
-8999(7)
-8266(3)
-7230(3)
-7524(3)
-5646(4)
-5939(3)
-4942(3)
-2509(3)
-4579(4)
-7292(5)
-8140(3)
-8229(3)
-5173(4)
-6598(4)
-3533(4)
-8089(4)
-7623(5)
-6576(5)
-10017(5)
-7459(6)
-9532(5)
-9015(5)
-8508(5)
-7754(5)
-8491(5)
-8795(4)
-9568(4)
-5047(5)
-3847(5)
-2712(4)
-4558(5)
-848(5)
-3070(6)
-4085(4)
-2843(5)
-2090(4)
-1963(5)
-3208(5)
-3950(5)
-5062(4)
-3957(4)
-3226(4)
y
-4502(1)
-4784(1)
-1871(3)
-2560(4)
-2082(4)
-5517(2)
-5284(2)
-7453(2)
-6934(3)
-4428(2)
-4105(2)
-5346(2)
-5992(2)
-3417(3)
-3590(3)
-5134(2)
-4371(3)
-7188(2)
-5659(3)
-5614(3)
-7403(3)
-7101(4)
-5482(4)
-7613(4)
-8212(4)
-6121(3)
-6489(4)
-7275(4)
-7909(3)
-7578(3)
-6791(3)
-4111(3)
-5553(3)
-5180(3)
-2797(3)
-4322(4)
-5134(4)
-3686(3)
-3678(3)
-4480(4)
-4715(4)
-4857(4)
-4069(3)
-6426(3)
-6413(3)
-7101(3)
z
-1033(1)
-1762(1)
-997(3)
-995(4)
-1631(3)
-1395(1)
-720(1)
-1747(1)
-331(1)
-2114(1)
-1441(1)
-1291(1)
-2645(1)
-946(2)
-1674(2)
-2386(1)
-422(1)
-1032(2)
-1969(2)
-948(2)
-1315(2)
-527(2)
-541(2)
245(2)
-1339(2)
-674(2)
-204(2)
-257(2)
-545(2)
-1036(2)
-996(2)
-1886(2)
-2458(2)
-1704(2)
-2246(2)
-1740(3)
-3249(2)
-2198(2)
-1937(2)
-1975(2)
-2504(2)
-2730(2)
-2698(2)
-1499(2)
-1739(2)
-1770(2)
U(eq)
36(1)
31(1)
148(3)
189(4)
157(3)
36(1)
40(1)
38(1)
49(1)
36(1)
37(1)
48(1)
46(1)
60(1)
51(1)
39(1)
58(1)
30(1)
32(1)
33(1)
32(1)
37(1)
44(1)
56(2)
46(2)
34(1)
42(1)
40(1)
41(1)
34(1)
34(1)
31(1)
35(1)
36(1)
44(1)
56(2)
51(2)
36(1)
40(1)
40(1)
42(1)
38(1)
35(1)
31(1)
30(1)
34(1)
124
Table 2.5.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 6. a
atom
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(501)
C(502)
C(50D)
C(503)
C(504)
C(505)
C(506)
C(51D)
C(52D)
C(507)
C(508)
0(601)
C(601)
C(602)
C(603)
C(604)
y
x
-3616
-4721
-5430
-2050
-5105
-7949
-8665
-8212
-8561
-7716
-8092
-8053
-4364
-3472
-4754
-5715
-3121
-4324
-8524
-8202
-8887
-9999
-9592
(5)
(5)
(4)
(5)
(5)
(6)
(8)
(7)
(18)
(24)
(12)
(9)
(14)
(11)
(25)
(19)
(18)
(15)
(23)
(38)
(62)
(48)
(27)
-7803
-7853
-7147
-7104
-8627
-3221
-2435
-4593
-5162
-5118
-5997
-5956
-5115
-4809
-4781
-4244
-4013
-3708
-4476
-3404
-3160
-3508
-4169
z
(3)
(3)
(3)
(4)
(3)
(4)
(5)
(4)
(10)
(12)
(6)
(5)
(10)
(8)
(18)
(13)
(12)
(10)
(15)
(25)
(36)
(33)
(18)
-1540 (2)
-1284 (2)
-1277 (2)
-2055 (2)
-1039 (2)
-1279 (3)
-1221 (4)
-2805 (2)
-3219 (5)
-3215 (7)
-3063 (3)
-2556 (3)
-274 (5)
81 (4)
383 (9)
51 (7)
-221 (7)
-350 (6)
637 (8)
443 (14
729 (22
606 (18
665 (9)
U(eq)
34 (1)
32 (1)
31 (1)
43 (1)
40 (1)
51 (2)
80 (2)
59 (2)
82 (6)
79 (8)
118 (4)
86 (3)
164 (5)
122 (4)
131 (9)
94 (7)
104 (6)
83 (5)
196 (8)
193 (15
287 (27
244 (20
128 (8)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
125
Table 2.6. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 8. a
atom
Cu(1)
Cu(2)
F(701)
F(702)
F(703)
F(704)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
x
544(1)
-647(1)
2595(3)
1733(3)
2636(3)
1605(3)
-1155(3)
-95(3)
-2300(3)
-333(3)
-114(3)
1010(3)
1337(3)
-842(3)
1194(3)
1470(3)
-521(3)
-1696(3)
-1352(3)
247(3)
-817(4)
-2051(4)
-949(4)
-1182(4)
-1102(4)
-3374(4)
-1308(4)
-1030(4)
-1343(4)
-2248(4)
-2464(4)
-2205(4)
-343(4)
-275(5)
-3745(4)
-4653(5)
-1478(4)
-1145(5)
606(4)
-126(4)
1079(4)
1385(4)
2430(4)
-17(4)
1064(4)
1789(4)
y
2352(1)
2940(1)
4023(3)
4795(2)
4934(2)
4260(2)
2468(2)
1870(2)
1710(2)
355(2)
3226(2)
2748(2)
1530(2)
2519(2)
2998(3)
1712(2)
3769(2)
3289(2)
1001(2)
2030(2)
2014(3)
1344(3)
593(3)
2008(3)
-160(3)
1267(3)
1652(3)
971(3)
486(3)
549(3)
1204(3)
1666(3)
2026(4)
2358(5)
842(4)
908(4)
-716(3)
-1328(3)
3096(3)
2504(3)
1963(3)
4020(3)
2117(3)
3242(3)
3394(3)
3003(3)
z
7104(1)
6507(1)
4382(3)
4440(3)
3789(3)
3386(3)
7086(3)
7554(3)
5735(3)
6799(3)
5827(3)
6433(3)
5505(3)
4095(3)
8036(3)
7431(3)
7274(3)
5856(3)
6246(3)
4795(3)
7473(4)
6231(4)
6822(4)
8639(4)
7783(4)
6486(4)
7892(4)
8059(4)
7438(3)
7125(4)
6832(4)
7477(4)
9147(4)
9860(5)
5840(4)
5562(5)
7331(4)
7692(4)
5914(4)
4309(4)
5092(4)
5810(4)
4901(4)
3314(4)
5418(4)
5390(4)
U(eq)
32(1)
34(1)
79(2)
72(2)
68(1)
71(1)
38(1)
36(1)
42(1)
36(1)
36(1)
36(1)
38(1)
39(1)
59(2)
47(1)
52(1)
50(1)
29(1)
26(1)
30(2)
31(2)
29(2)
36(2)
33(2)
36(2)
29(2)
28(2)
26(2)
30(2)
32(2)
33(2)
46(2)
74(3)
50(2)
68(3)
37(2)
48(2)
29(2)
30(2)
31(2)
39(2)
38(2)
39(2)
30(2)
33(2)
126
Table 2.6.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 10 3 ) for 8.a
atom
(209)
(210)
(211)
(212)
(213)
(214)
(215)
(216)
(217)
(218)
(301)
(302)
(303)
(304)
(305)
(306)
(307)
(308)
(401)
(402)
(403)
(404)
(405)
(406)
(407)
(408)
(501)
(502)
(503)
(504)
(505)
(506)
(507)
(508)
(801)
(802)
(803)
(804)
(801)
(701)
x
1621(4)
1204(4)
405(4)
547(4)
769(5)
1155(6)
-192(6)
-580(6)
2400(4)
3145(5)
-559(4)
-251(4)
-421(4)
-895(4)
-1223(4)
-1036(4)
-111(5)
-1762(5)
1622(7)
2383(8)
2163(10)
1548(7)
1311(6)
1942(7)
2567(7)
2263(5)
-572(7)
-369(9)
-448(9)
-732(8)
-2433(5)
-3047(7)
-2661(5)
-1825(6)
749(14)
1155(14)
1305(15)
1092(14)
686(11)
2139(6)
y
2440(3)
2684(3)
2985(3)
3529(3)
4506(4)
5085(4)
2777(4)
3051(5)
1586(3)
1197(4)
1513(3)
1518(3)
1042(3)
560(3)
537(3)
1022(3)
1053(4)
6(3)
2809(5)
3206(6)
3748(8)
3561(5)
1067(4)
735(5)
1157(5)
1791(4)
3715(4)
4357(5)
4772(5)
4403(4)
3312(5)
3473(6)
3737(5)
3515(5)
2(12)
-90(12)
-537(13)
-1078(12)
-766(10)
4503(5)
z
4862(4)
4091(4)
4085(4)
4642(4)
5844(5)
6258(6)
2678(4)
1930(4)
4357(4)
4566(5)
5513(3)
4908(4)
4384(3)
4502(4)
5100(4)
5607(4)
3721(4)
5172(4)
8760(5)
8935(7)
8504(9)
7859(6)
7425(8)
7274(9)
7292(10)
7331(6)
8012(5)
8349(6)
7718(6)
7053(5)
6070(5)
5409(6)
4869(5)
5119(5)
9475(14)
8895(14)
8458(14)
8827(14)
9347(11)
3988(6)
U(eq)
32 (2)
32 (2)
31 (2)
35 (2)
63 (3)
75 (3)
63 (3)
71 (3)
45 (2)
61 (2)
26 (2)
28 (2)
28 (2)
35 (2)
32 (2)
29 (2)
45 (2)
44 (2)
79 (3)
108 (4)
151 (6)
97 (4)
95 (4)
122 (5)
147 (7)
63 (3)
74 (3)
113 (5)
119 (5)
85 (3)
63 (3)
96 (4)
68 (3)
76 (3)
159 (8)
154 (8)
166 (9)
156 (8)
210 (7)
52 (3)
aNumbers in parentheses are estimated standard deviations of the
last significant figure. bU(eq) is defined as one third of the
trace of the orthogonali zed Uij tensor.
127
Table 2.7. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A2 x 103) for 9.a
atom
x
Cu (1)
4086
3146
3054
4008
3460
3389
2888
3599
2846
4135
3698
4407
5279
3870
4866
3276
2546
3119
2458
3000
3487
4603
3115
2953
3667
2437
3471
2054
2748
3066
3234
2755
2519
2324
2767
2425
2182
1735
3588
3899
4184
4313
5082
4437
5944
4398
Zn(1)
S(501)
F(501)
F(502)
F(503)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(501)
0(502)
0(503)
0(504)
0(505)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
z
y
(1)
(1)
(1)
(2)
(2)
(2)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
6891
7655
8413
8431
7705
8858
6677
6121
5875
4657
8306
7748
6904
7785
6390
7866
8233
9145
8237
7420
5227
7337
6144
5393
4739
5733
3607
4848
5495
4786
4334
4211
4946
5374
5930
6133
4417
4447
3025
2387
8255
7899
7427
9539
8086
9028
(1)
(1)
(1)
(3)
(2)
(2)
(2)
(2)
(2)
(1)
(2)
(2)
(1)
(2)
(2)
(2)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(4)
(2)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
1620 (1)
1235 (1)
2373 (1)
2829 (2)
3166 (2)
3280 (1)
1355 (1)
1728 (1)
223 (1)
1133 (1)
1001 (1)
1365 (1)
699 (1)
-245 (1)
1862 (1)
2043 (1)
2563 (2)
2201 (2)
1231 (1)
415 (1)
655 (1)
190 (1)
1580 (2)
531 (2)
1052 (2)
2180 (2)
1550 (2)
393 (2)
1702 (2)
1814 (2)
1343 (2)
972 (2)
789 (2)
1260 (2)
2656 (2)
3107 (2)
-87 (2)
-505 (2)
1139 (2)
1369 (2)
1109 (2)
-54 (2)
488 (2)
1279 (2)
581 (2)
-585 (2)
U(eq)
38(1)
35(1)
49(1)
96(1)
114(2)
103(2)
39(1)
37(1)
34(1)
32(1)
37(1)
39(1)
32(1)
39(1)
49(1)
54(1)
101(2)
85(1)
50(1)
50(1)
25(1)
26(1)
31(1)
29(1)
29(1)
42(1)
36(1)
37(1)
34(1)
35(1)
29(1)
31(1)
31(1)
36(1)
58(1)
84(2)
42(1)
51(1)
38(1)
53(1)
34(1)
30(1)
26(1)
48(1)
35(1)
42(1)
128
Table 2.7.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 9. a
atom
(207)
(208)
(209)
(210)
(211)
(212)
(213)
(214)
(215)
(216)
(217)
(218)
(301)
(302)
(303)
(304)
(305)
(306)
(307)
(308)
(401)
(402)
(403)
(404)
(501)
(502)
(503)
(504)
(505)
(601)
(602)
(601)
x
4544(2)
5139(2)
5339(2)
5187(2)
4579(2)
4373(2)
4538(3)
4345(3)
4547(2)
4277(3)
6243(2)
6793 (2)
4058(1)
4419(2)
4622(2)
4456(2)
4089(2)
3891(2)
4995(2)
3902(2)
5362(2)
5801(3)
5556(3)
4987(3)
3503(3)
1938(2)
1563(3)
1860(3)
2415(2)
5176(5)
5334(6)
5000
y
8877(2)
8664(2)
8186(2)
8569(2)
8652(2)
9120(2)
9422(3)
10109(3)
8652(3)
9022(3)
7672(2)
7412(3)
6269(2)
6589(2)
6207(2)
5485(2)
5152(2)
5559(2)
6549(2)
4379(2)
6796(3)
6270(4)
5536(4)
5673 (3)
8356(3)
7930(4)
8552(6)
9200(4)
8999(3)
3614(7)
2880(7)
2409(10)
z
919 (2)
943 (2)
495 (2)
-18 (2)
-74 (2)
372 (2)
1826 (2)
2135 (2)
-1082 (2)
-1551 (2)
174 (2)
375 (2)
427 (1)
107 (2)
-304 (1)
-378 (2)
-65 (2)
338 (1)
-675 (2)
-177 (2)
1921 (2)
1839 (3)
1870 (3)
1689 (2)
2931 (2)
1320 (3)
1259 (6)
1213 (4)
1083 (2)
2277 (4)
2165 (5)
2500
U(eq)
36 (1)
35 (1)
28 (1)
32 (1)
32 (1)
39 (1)
61 (2)
79 (2)
52 (1)
69 (2)
35 (1)
52 (1)
22 (1)
25 (1)
25 (1)
29 (1)
26 (1)
24 (1)
37 (1)
38 (1)
52 (1)
85 (2)
86 (2)
66 (2)
66 (2)
86 (2)
202 (7)
111 (3)
61 (2)
163 (4)
168 (5)
264 (8)
aNumbers in parentheses are estimated standard deviations of the
last significant figure. bU(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
129
Table 2.8. Atomic coordinates (x 104) and equivalent isotropic
displacement parameters (A 2 x 103) for 11.a
atom
x
CUl
CUl'
ZN1
C(401)
C(402)
C(403)
C(406)
C(407)
C(41)
C(42)
C(43)
C(44)
C(45)
C(404)
C(405)
S(501)
F(501)
F(502)
F(503)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(501)
0(502)
0(503)
930(2)
1310(2)
919(1)
1642(12)
1166(15)
2681(11)
1795(40)
2593(13)
2421(8)
1974(10)
2223(13)
1586(21)
1206(11)
2829(5)
2288(6)
2606(1)
3120(4)
4070(4)
3994(3)
1206(2)
1307(2)
-429(2)
-66(2)
-103(2)
57(2)
-1785(2)
-2275(2)
2108(3)
3103(4)
2042(4)
0(504)
948(2)
N(101)
N(201)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
-283(2)
-2119(2)
1444(3)
1(3)
215(3)
3042(3)
1181(3)
740(3)
2009(3)
1966(3)
1083(3)
971(3)
855(3)
1713(3)
3505(3)
y
4667(1)
4532(1)
4644(1)
4745(5)
4208(13)
4570(7)
3664(17)
4047(8)
4453(6)
3974(5)
4696(6)
3849(7)
4476(7)
4328(3)
3771(3)
3784(1)
4298(3)
4368(3)
3628(2)
5388(1)
5322(1)
6346(1)
6162(1)
4168(1)
4210(1)
4584(1)
4606(1)
4272(2)
3521(2)
3429(2)
z
U(eq)
8648(1)
8484(1)
6303(1)
10030(9)
9850(12)
10350(12)
9962(31)
9801(11)
9695(8)
9452(8)
10484(9)
10083(15)
10226(12)
11318(4)
11093(5)
7091(1)
5959(5)
7354(6)
6611(4)
6708(2)
8136(2)
5693(2)
8630(2)
6202(2)
7648(2)
8004(2)
5012(2)
7160(3)
7932(4)
6356(4)
38(1)
42(1)
29(1)
53(3)
89(7)
64(4)
201(25)
68(4)
54(3)
55(3)
65(3)
73(6)
68(4)
85(2)
93(2)
64(1)
184(3)
175(3)
126(2)
37(1)
40(1)
37(1)
42(1)
36(1)
40(1)
43(1)
33(1)
60(1)
113(2)
103(2)
4656(1)
5078(2)
40(1)
6303(1)
4596(1)
5563(2)
6493(2)
6379(2)
5929(2)
7034(2)
7274(2)
6104(2)
6393(2)
6749(2)
7164(2)
6868(2)
6497(2)
5508(2)
7162(2)
6490(2)
7518(3)
6481(3)
8111(3)
7939(3)
9304(3)
5991(3)
7747(3)
8590(3)
8410(3)
7657(3)
6772(3)
6926(3)
8663(4)
28(1)
26(1)
30(1)
29(1)
30(1)
37(1)
40(1)
38(1)
29(1)
32(1)
31(1)
32(1)
31(1)
31(1)
49(1)
130
Table 2.8.(cont'd) Atomic coordinates (x 10 4 ) and equivalent
isotropic displacement parameters (A2 x 10 3 ) for 11.a
atom
C(114)
C(115)
C(116)
C(117)
C(118)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(501)
x
4522(4)
-82(4)
-73(4)
343(4)
362(5)
-252(3)
-2302(3)
-2002(3)
-103 (3)
-2538(3)
-3225(3)
-835(3)
-1261(3)
-2184(3)
-2897(3)
-2520(3)
-1599(3)
715(4)
1403(4)
-4164(3)
-4837(3)
-3478(3)
-3608(4)
-1207(3)
-2066(3)
-2897(3)
-2839(3)
-1989(3)
-1172(3)
-3840(3)
-1951(4)
3485(6)
y
5422
7669
8087
7394
7558
3997
4342
4323
2997
3554
3588
3464
3392
3703
3564
3725
3415
2966
2511
3880
3681
3807
3784
5452
5191
5484
6054
6333
6022
5198
6956
4028
z
8800(4)
5713(4)
5014(4)
9232(3)
10149(4)
6883(3)
5652(3)
7309(3)
6839(3)
8001(3)
4600(3)
6730(3)
7445(3)
7251(3)
6296(3)
5583(3)
5763(3)
7749(4)
7755(5)
4263(3)
3322(3)
7893(3)
8782(4)
6841(3)
6519(3)
6231(3)
6276(4)
6586(3)
6861(3)
5875(4)
6630(5)
6733 (7)
U(eq)
(2)
(1)
(2)
(1)
(2)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(1)
(1)
(1)
(2)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
aNumbers in parentheses are estimated standard deviations of the
last significant figure. bU(eq) is defined as one third of the
trace of the orthogonalized Uij tensor.
131
Table 2.9. Selected electrochemical data for a range of copper redox couples.
72-
Ph
0
N\\
N--CU
Cu
aa -
0
bI
O
NCCH 3
C
d
d
N-
'u- N
p r---N
i-Pr
e
i-Pr
i-Pr
i-Pr'-
h
I+
-Pr
pY
N /ON\0 N
r/
CU-PY
PY-Cu
PY
PY
I
~A
'-
7+
(0rt-Bu
+
NCu-NCCH3
f
N-N
H-B.N-N ,,"Cu--NCCH3
N-Nt-Bu
i-Pr
Entry
Redox Couple
h
4)--Bu
Solvent/Electroyte
Lit. Ref. Elec.
Lit.
E 1 /2
Scaled
a
E1/ 2b
ref.
Pr4NC104/0.1 M, DMF
SCE
-1210
-1 7 7 0 c
54
(CuIICuI)/(CuICu I)
Bu4NC104/ 0.1 M, DMF
NHE
-517
-1 3 1 8 d
17
I)
Et4NC104/ 0.1 M, DMF
SCE
-470
-1030c
60
Bu4NPF6/0.2 M, DMF
Cp2Fe+/
-628
-51 8 e
56
Ag/AgNO3
-587
-497f
59
SCE
+70
-4 9 0 c
52b
Cp2Fe+/
-218
-218
This
a
CuII/CuI
b
c
(CuIICuI)/(CuICu
d
CuII/Cu I
Cp 2Fe,DMF
e
f
(CuIICuI)/(CulCu
I)
Bu4NPF6/0.2 M, DMF
(CuIICuI)/(CulCu
I)
Bu4NPF6/ 0.5 M,
CH 2C12
I
7
(CuIICuI)/(CuICu )
g
(CuIICuI)/(CuICu
I)
h
CuII/Cu I
i
CuII/Cul
Bu4NPF6/ 0.5 M, THF
Work
Cp2Fe,THF
Ag/AgCl
+310
-206g
24
Bu4NPF6/ 0.5 M, MeCN
SCE
+360
-2 0 0 c
57
Bu4NOTf/0.1 M,
SCE
+910
+109c
55
Not Given/DMF
CH 2Cl2/MeCN (9:1)
CuII/Cu
Bu4NBF 4 / 0.1 M, MeCN
SCE
+690
+130c
58
aE 1 / 2 values are listed in mV. bAll literature potentials have been scaled to Cp2Fe+/Cp 2 Fe in THF.
CCp 2 Fe+/Cp 2Fe = +560 mV vs. SCE in THF (see ref. 62). dSCE = +241.2 mV vs. NHE (see ref. 61).
eCp 2 Fe+/Cp 2 Fe in DMF = -110 mV vs. Cp2Fe+/Cp2Fe in THF (see ref. 62).fCp2Fe+/Cp 2Fe = +20 mV
vs. Ag/AgNO3 (see ref. 56). gAg/AgC1 = -44.2 mV vs. SCE (see ref. 61).
j
132
Table 2.10. EPR g values and copper hyperfine coupling constants for 7, derived from
a simulation of the frozen solution X-band spectrum acquired at 77 K.
Compd.
gi
g2
g3
A1Cu (Hz)
A2 Cu (Hz)
A 3 Cu (Hz)
7
2.030
2.158
2.312
20.0
55.0
122.5
133
F3 C
+ (BF 4)"
0
o
0
Cu---O
!O-Cu-
4,5
Cu-O
1 AgO 2CCF 3
THF
1AgOTf
or
1 Et4NCN/1 Cu(OTf) 2
THF
0
1o-zo
oC u
5,o-4~
I
O
4
7,8
1 AgBF 4
THF
O-Cu-O
Cu
NCCH 3
1 or2
1 Et4 NCN/
1 Fe(OTf) 2(MeCN)
excess NB
1 Et
4 NCN/
F3C.S
1 Zn(OTf) 2
THF
OO
0
OcuO "O
F3C ,S.-4
O
NCCH 3
10a
Scheme 2.1.
q-&-Cu'O
-0
.OZn-
O
H2
exces!s
NB
OH 2
9
134
1200
1000
800
E
o
600
400
200
400
600
800
1000
1200
1400
1600
1800
2000
X (nm)
Figure 2.1. Electronic absorption spectrum of [Cu 2 (XDK)(g-OTf)(THF) 2 ] (4), 0.74 mM
in THF.
135
2000
1500
1000
500
400
600
800
1000
1200
1400
1600
1800
2000
k (nm)
Figure 2.2. Electronic absorption spectrum of [Cu 2 (XDK)(g-O 2 CCF 3 )(THF) 2 ] (6), 0.74
mM in THF.
136
1600
1400
1200
1000
E
800
oC.
600
400
200
400
600
800
1000
1200
1400
1600
1800
2000
X (nm)
Figure 2.3. Electronic absorption spectrum of [Cu 2 (XDK)(THF) 4 ](BF 4 ) (7), 0.47 mM in
THF.
137
25
I
I
I
I
= 3.3142 + 3.608x R= 0.996
Sy
O
y = 0.70605 + 0.30735x R= 0.99578
-----
20 I
I
-O
0
15
-OTf complex
- -*-
E
-
o
STHF Std.
10
0
0
-
I
*------4------*-------------
I
I
I
I
I
conc (mM)
Figure 2.4. Conductivity plots for [Cu 2 (XDK)(g-OTf)(THF) 2 ] (4) and Bu 4 NPF 6 in THF
at 296K.
138
12
10
-9
-
- - BF4 complex
+THF3.8544
5.0 Std.
566x R= 0.99557
-
0.5
-
y = 2.6312 + 4.1186x R= 0.99592
1.5
2.5
conc (mM)
Figure 2.5. Conductivity plots for [Cu 2 (XDK)(THF)1(BF
4
4 ) (7) in THF and Bu 4 NPF 6 in
THF at 296 K.
139
F(401)
0(403)
F(402)
F(403)
S(401)
0(401)
0(502)
Cu(1) 0(102)
0(202)
0(402)
0(101)
Cuf2)
0(501)
0(201)
Figure 2.6. ORTEP diagram of [Cu 2 (XDK)(g-OTf)(THF) 2 ] (4) with 50% thermal
ellipsoids. Atoms represented as open circles were refined isotropically.
140
F(401)
0(401),
F(403)
40(402)
Figure 2.7. ORTEP diagram of [Cu 2 (XDK)(g-O 2 CCF 3 )(THF) 2 ] (6) with 50% thermal
ellipsoids. Atoms represented as open circles were refined isotropically.
141
Figure 2.8. ORTEP diagram of [Cu 2 (PXDK)(THF)4](BF 4 ) (8) with 50% thermal
ellipsoids. The PXDK propyl substituents adjacent to the copper coordination
spheres have been omitted for clarity, and atoms represented as open circles were
refined isotropically.
142
CD
02
[CuFe(PXDK)(OTf)(NB)(MeCN)]
2
(10a)
4W
V1los
cm-1
C:
1550 cm "'
[CuFe(PXDK)(02C(4-tert-Bu)-Ph))(NB)(MeCN)]ln(10b, n = 1 or 2)
1026 cm "'
10b -10a
-
C
1538 cm "1
1800
1600
1400
1200
Wavenumber (cm-)
1000
800
Figure 2.9. (Top) Stacked IR spectra of 10a and 10b in the carboxylate-vco and the
triflate-vso regions; (Bottom) Difference IR spectrum of 10b-10a.
143
Figure 2.10. ORTEP diagram of [CuZn(PXDK)(OTf)(THF) 2 (H 2 0)] (9) with 50%
thermal ellipsoids. One of the carbon atoms of the THF ligated to Znl was refined
isotropically; it is represented as an open circle.
144
HbU3)
F(501)
R
S(501)
0(503)
/S5
C(M
F(501)
C(41)
0(503)
0(501)
C(401)
C(402)
0(501)
C(42)
CU(1)
0ZN(1)
CUM 0(102)
(101)
0(504)
0(202)
0(201)
CU(1')
0(102)
0(101)
.
0(202)
ZN()
0(201)
Figure 2.11. ORTEP diagrams of [CuZn(PXDK)(OTf)(NB)(H 20)] (11) with 50%
thermal ellipsoids, showing the two orientations of the copper-norbomene
fragment (see the Experimental section for details).
0(504)
145
30
20
10
0
-10
-20
-30
-40
-50
II
200
.
.
I.
II
I
SI
I
I
II
i
I
II
-200
-400
E (V) vs. Cp2Fe*/Cp 2Fe
Ii
.
I
II
-600
Figure 2.12. Cyclic voltammogram of 10 mM [Cu 2 (XDK)] in THF with 0.5 M
(Bu 4 N)(PF6) as supporting electrolyte and an anodic scan speed of 50 mV/sec.
146
y = -7.4467 + -4.6968x R= 0.99993
-
- - - y = 10.712 + 2.6102x R= 0.99809
--
Ipa
-+-
-Ipc
72
-40
64
56
-60
*-
48
o
-5
CL
40
p
-80
32
24
I
I
I
.
.
-100
16
.
.
•
I
I I
I
I
I
II
I
|
|
|
|
I
I
I
20
10
V1/2
Figure 2.13. Plot of anodic and cathodic currents versus (scan speed) 1 / 2 for
[Cu 2 (XDK)].
-120
25
147
25
20
15
10
5
0
-5
-10
-15
200
0
-200
-400
E (mV) vs. Cp 2 Fe+/Cp Fe
-600
-800
Figure 2.14. Cyclic voltammogram of 10 mM [Cu 2(XDK)(THF) 4](BF 4) (7) in THF with
0.5 M (Bu 4N)(PF6 ) as supporting electrolyte and a cathodic scan speed of 50 mV/sec.
148
y = -5.2207 + -1.5477x R= 0.99793
-
- -y = 6.3699 + 2.1383x R= 0.999
--
Ira
- -Ipc
55
-15
50
-20
45
-25
40
-5-
35
-30
30
-35
25
20
-40
20
V
1/2
Figure 2.15. Plot of anodic and cathodic currents versus (scan speed) 1/ 2 for
[Cu 2 (XDK)(THF) 4 (BF 4 ) (7).
25
149
15
10
5
0
-5
-10
400
I
I
200
I
I
I
I I
I
I
I
-200
I
I
I
I
-400
I
I
I
I
-600
I
I
I
-800
E (mV) vs. Cp 2Fe/Cp 2Fe'
Figure 2.16. Cyclic voltammogram of 10 mM [Cu 2 (XDK)(g-OTf)(THF) 2 ] (4) in THF
with 0.5 M (Bu 4 N)(PF 6 ) as supporting electrolyte and a cathodic scan speed of 50
mV/sec.
150
-
-
y = -2.4326 + -1.054x R= 0.99715
-----
Ipa
-y = 3.7912 + 1.4252x R= 0.99917
--
- Ipc
40
-5
35
-10
30
-15
o
--
25
-20
20
-25
15
10
..........
-30
10
15
V
20
25
1/2
Figure 2.17. Plot of anodic and cathodic currents versus (scan speed) 1/ 2 for
[Cu 2 (XDK)(g-OTf)(THF) 2] (4).
151
30
20
10
0
-10
-ZU
600
I
II
'''''''''''''~''''"
I
I
I
I
I
400
200
0
-200
-400
'''''''
I
-600
I,
I
-800
E (mV) vs. Cp 2 Fe/Cp2 Fe
Figure 2.18. Cyclic voltammogram of 10 mM [Cu 2 (XDK)(g-OTf)(THF) 2 ] (4) in THF (2
cycles) with 0.5 M (Bu 4 N)(PF 6 ) as supporting electrolyte and a cathodic scan speed of
200 mV/sec
152
10
5
E
0
-5
'
400
I
I
I
l
200
.
I
1. 1
I
I
0
I
I
*
I
,
.
*
.
-200
.
*
.
I
.
*III
.
-400
*I
.
.
.
.
-600
.
*
.
I
I
.
-800
-1000
E (mV) vs. Cp 2 Fe/Cp 2 Fe'
Figure 2.19. Cyclic voltammogram of 10 mM [Cu 2 (XDK)(g-O 2 CCF 3 )(THF) 2] (6) in
THF with 0.5 M (Bu 4 N)(PF 6 ) as supporting electrolyte and a cathodic scan speed of
200 mV/sec.
153
2000
2500
3000
H (Gauss)
3500
4000
Figure 2.20. X-band EPR spectra of 1 mM [Cu 2 (XDK)(THF) 4 ](BF 4 ) (7) as a frozen
solution at 77 and 9 K, along with a simulation of the 77 K data. See Table 2.10 for
simulation parameters.
154
3500
3000
H (Gauss)
2500
2000
4000
S9K
2250
2500
2750
3000
3250
3500
Figure 2.21. X-band EPR spectra of [Cu 2 (XDK)(THF)4 ](BF4) (7) as a powdered solid at
296, 77, and 9 K, along with a simulation of the 77 K data.
155
10830
11800
12770
13740
(7) as a frozen solution
Figure 2.22. Q-band EPR spectrum of [Cu 2 (XDK)(THF)1(BF4)
4
at 2K.
156
t
A-1-
Figure 2.23. Contour plots derived from extended Hiickel calculations for the SOMO
of [Cu 2 (Q-O2 CCH 3 )2(OMe2)4], a simplified model of 7 and 8.
157
Figure 2.24. Contour plot derived from extended Hiickel calculations for the
SHOMO of [Cu 2 (g-O 2CCH 3) 2(OMe2)4 ].
158
7
89OH
OH
/O-.qZCu
-1
OH2
l
l
OH2
OH
O---,Cu---Cuu-0O
OH2
OH 2
- 0
Xz-
OH
-1 1
-12-1
3-
--
34----
.--
-14
-
-
Cu(ll) Fragment
Cu(I) Fragment
1.8
2
2.2
2.4 2.6 2.8
3
Cu...Cu Distance (A)
3.2
3.4
Figure 2.25. Fragment molecular orbital diagram and a Walsh diagram for
[Cu 2 (OH)2(OH2)2 (OMe2 )4], a simplified model of 7 and 8.
Chapter III
Modeling the Hperoxo Intermediate of Soluble Methane Monooxygenase:
Preparation of Sterically Hindered Diiron(II) Tetracarboxylate Complexes, and Their
Reactivity Toward Dioxygen
160
Introduction
Over the last few decades, a class of carboxylate-bridged diiron proteins has
been discovered that utilizes dioxygen for a variety of functions, ranging from 02
transport to the selective catalytic oxidation of organic substrates by hydroxylation,
epoxidation, or hydrogen atom abstraction processes. 1-5 This diversity is aptly
represented in three of the most intensively studied of these proteins, hemerythrin,
ribonucleotide reductase, and methane monooxygenase. Hemerythrin (Hr) is the
dioxygen carrier protein in marine invertebrates. The reduced protein has a [Fe2(gLOH)(I9-O2CR) 2(His) 5] + donor set, and in the oxidized form 02 is bound as a terminal
il-hydroperoxide, hydrogen bonded to the oxo bridge (eq 1).
HN
H
HN -
H-N- N
NH
N
N,
02
N
NO
O
0
H-O
'O
0IN
.
O
Oi,.
0
H
(1)
\(
H
Ribnucleotide reductases are essential for reducing ribonucleotides to
deoxyribonucleotides, which are used in DNA biosynthesis. The E. coli form of this
enzyme houses a diiron active site in the R2 subunit (RNR-R2). Here 02 is activated
and one of its oxidizing equivalents is used to generate a tyrosyl radical, which in
turn transfers an electron from the R1 subunit, where the ribonucleotide reduction
is catalyzed. Methane monooxygenase (MMO) is used by obligate methanotrophic
bacteria to oxidize methane selectively to methanol. These bacteria use methane as
their sole source of carbon and energy. This mixed function oxidase incorporates
one of the oxygen atoms from dioxygen into methanol and the other into water (eq
2). The soluble form (sMMO) contains a diiron center in the hydroxylase component
(MMOH), the site of methane oxidation.
CH 4 + 02 + NADH
+ H+
-
CH3 OH + H20
+ NAD +
(2)
161
Unlike hemerythrin, the RNR-R2 and MMOH enzymes contain oxygen-rich
coordination environments at their diiron active sites. In each protein four
carboxylate and two imidazole ligands are distributed about the two iron atoms. The
remainder of coordination sites are occupied by a variable number of water,
hydroxide, or oxo ligands, depending on the enzyme and its position in the catalytic
cycle. Depicted in Figure 3.1 are the active site structures of the diiron(II) forms of
RNR-R2 and MMOH, and the oxidized diiron(III) form of MMOH, each deduced
from X-ray crystal structural analyses. 6-8
A detailed mechanistic picture of the 02 activation process in RNR-R2 2,9,10
and sMMO 2,4,9, 10 is emerging as a result of the detection and spectroscopic
characterization of transient oxygen intermediates (Figure 3.2). For RNR-R2, the first
intermediate forms and decays within 35 milliseconds. 11 Based on the similarity of
its M6ssbauer and UV-vis spectra to those observed for a model complex and an
analogous intermediate in MMOH (vide infra), this species has been tentatively
assigned as a diiron(III) peroxo complex, the product of 02 binding to the fully
reduced diiron center combined with two-electron reduction. Intermediate X, which
forms subsequently after the peroxo, has M6ssbauer, 12 Q-band ENDOR,1 3 and
EXAFS 14 spectra consistent with an antiferromagnetically coupled Fe(III)Fe(IV)
center with at least one oxo bridge and a terminal water or hydroxide ligand. In
addition, X has an Fe...Fe separation of 2.5 A and at least one Fe-O distance of 1.8 A.
The EXAFS parameters are consistent with the presence of two or three single atom
bridges. This high-valent intermediate X is the direct precursor to catalytically active
RNR-R2 (RRact) and generates the active enzyme possibly by hydrogen atom
abstraction from Tyr-122, to afford an oxo-bridged diiron(III) center and the tyrosyl
radical. Presumably X is the product of peroxide 0-0 bond cleavage, but it is not clear
whether injection of an extra electron must accompany 0-0 bond scission or,
162
alternatively, whether a yet unobserved dioxodiiron(IV) species might be initially
generated. 10
For MMOH, a metastable diiron(III) peroxo intermediate (Hperoxo) has also
been identified as an early product of the 02 reaction chemistry, 5s but it forms and
decays more slowly than its RNR-R2 analog. 11 Hperoxo converts to a diiron(IV)
species termed Q (or MMOH-Q). 15 , 16 This intermediate, or a closely related
derivative, is believed to be the active substrate oxidant since Q is the last ironoxygen species detected prior to methane oxidation, and its decomposition is
accelerated by the presence of substrate. The structure of Q has been interrogated by
EXAFS, which revealed quite similar parameters to those observed for intermediate
X in RNR-R2.17 The EXAFS data do not provide unique structural infomation about
either high-valent intermediate, however, particularly regarding the coordination
of the oxygen ligands derived from 02.
Recent experiments on RNR-R2 and MMOH reveal that the two systems
share common oxygen intermediates, the fate of which is exquisitely regulated
according to their different oxidative functions. In one study, an RNR-R2 mutant
was prepared in which an aspartate residue in the active site was replaced with
glutamate, affording an MMOH-like coordination environment. 18 With this
modest change in the flexibility of a single carboxylate ligand, the D84E mutant
remarkably afforded a diiron(lI) peroxo that formed and decayed at rates comparable
to those of MMOH-Hperoxo, proceeding to form a stoichiometric amount of a stable
tyrosyl radical, most likely via intermediate X. These results lend credence to the
assignment of the initial 02 intermediate in native RNR-R2 as a diiron(III) peroxo
species, and reveal that the stability of the peroxo intermediates in RNR-R2 and
MMOH can be regulated by tuning the active site ligands.
In the other study, intermediate Q in MMOH was reduced radiolytically at
low temperature, while keeping the active site structure conformationally fixed in a
163
frozen solution. 19 This procedure provided a new spectroscopically distinct species,
termed Qx, having M6ssbauer parameters essentially identical to those of R2-X. This
result, coupled with the EXAFS studies of Q, suggests that R2-X and Q have very
similar structures, and that R2-X is derived from a Q-like analog by reduction with
an external electron. In this manner, the extra oxidizing equivalent in a
dioxodiiron(IV) intermediate could be quickly sequestered in RNR-R2 by an outer
sphere reduction, so that R2-X can generate a tyrosyl radical stable towards further
degradation by a metal-based oxidant. In contrast, both oxidizing equivalents of
MMOH-Q are retained for methane oxidation.
Considerable effort has been expended to prepare synthetic models for the
dioxygen intermediates described above for RNR-R2 and sMMO. The goals have
been to mimic their spectroscopic and structural features, and utimately their
oxidation chemistry. 1,5 The most notable systems reported to date include three well
characterized diiron(III) peroxo complexes and an Fe(III)Fe(IV) bis(p.-oxo) species, the
properties of which are summarized in Table 3.1. The peroxo complexes were all
prepared by exposure of the ferrous precursor to 02 at low temperature. 20- 22 They
have UV-vis spectra characterized by a broad charge-transfer band centered at ~600
nm (e ~ 2000 M-lcm-1), and resonance Raman 0-0 stretches at -900 cm - 1 . In
addition, X-ray structural studies revealed the peroxide to be bound symmetrically
in an eclipsed or gauche g-1,2 bridging mode for each complex.
The Fe(III)Fe(IV) bis(g-oxo) model was prepared from hydrogen peroxide and
a diiron(III) bis(p-oxo) "diamond core" precursor, possibly via a diiron(III)(p-oxo)(pperoxo) intermediate. 23,24 It has an antiferromagnetically coupled, valence localized,
S = 1/2 ground state and distinct M6ssbauer quadrapole doublets for the Fe(III) and
Fe(IV) ions. The electronic structure of the metal ions matches well with analogous
spectroscopic data accumulated for Qx and X, but it is not yet clear whether the
arrangement of oxo ligands in each system is the same.
164
Despite these recent advances, there are many deficiencies in the models for
RNR-R2 and sMMO. Most importantly, in no system where a peroxo has been
derived from the reaction of an iron(II) precursor with 02 has conversion to a high
valent Q- or X-like species been demonstrated, nor has hydrocarbon oxidation
chemistry been achieved. These shortcomings may stem from the fact that the
present model systems do not reproduce the ligand composition found at the RNRR2 and sMMO active sites; their soft, nitrogen-rich coordination environments
more closely resemble the active site residues in hemerythrin. The widely different
fates of the peroxo ligands in Hr, RNR-R2, and sMMO may be due in part to the
ability of the latter two systems, owing to their more basic, oxygen-rich donor sets, to
support higher iron oxidation states required for 0-0 bond cleavage. With this
hypothesis in mind, we were interested to investigate a carboxylate-rich model
system in the hope that it would more closely mimic the RNR/sMMO systems from
the dioxygen binding through 0-0 bond cleavage and substrate oxidation steps.
carboxylate-bridged
Recently,
complexes
diiron(II)
having
the
xylylenediamine bis(Kemp's triacid imide) (H2XDK) ligand system were described,
and their reactivity towards dioxygen explored in a preliminary manner.25 A family
of diferrous tris(carboxylate-bridged) complexes was obtained which matched the
composition of amino acid ligands at the MMOH active site. When one of these
derivatives was exposed to 02 at low temperature in THF, the solution flashed deep
purple, but quickly decayed to a red-orange color in less than 30 s (eq 3). Monitoring
this reaction by stopped-flow UV-vis spectroscopy revealed the build-up and
t-Bu
\
Fe
N
-
Fe
t-Bu
O
0o
/ X
0
PXDK
N01
N
02
T
THF,-80oC
S
purple intermediate
-
<155s
red/orange
decompostion
product
(3)
165
decay over 10 s of an intermediate with an optical band centered at 650 nm. This
species was tentatively assigned as a diiron(III) peroxo, but its inherent instability
precluded any further characterization or functional reactivity studies.
In previous investigations from this laboratory, we have focused on the
thermal decomposition of well defined diiron(III) peroxo complexes. 26,27 Kinetic
studies revealed the decay to have second order behavior in the peroxo, resulting in
the extrusion of 0.5 equivalents of 02 and cleanly yielding diiron(III) oxo-bridged
derivatives. Since bimolecular decay pathways are typically retarded by
implementing sterically more hindered ligands, we modified the diiron XDK ligand
system with bulkier R groups with the aim of stabilizing the incipient peroxo
intermediate. Presented here are the synthesis and characterization of sterically
R
R
OH o
,,
o0
H2 XDK; R = methyl (1)
SR
H2PXDK; R=propyl (2)
H2 BXDK; R = benzyl (3)
hindered diiron(II) tetracarboxylate complexes and studies of their reactivity toward
02 to form stable peroxo adducts. A detailed account of their reactivity toward
electrophilic, nucleophilic, and hydrocarbon substrates is in the following chapter. 28
Experimental Section
General Considerations. The compounds H 2 XDK (1),29 H 2 PXDK (2),25,
H 2BXDK (3),30 1-phenylcyclohexanecarboxylic acid, 31 and [FeTp3,5-iPr 2 (0 2CCH 2Ph)]20
were prepared according to literature procedures. The thallium(I) salts of the
carboxylic acid ligands were obtained as described in the literature or by analogous
procedures,30
,32
and each was identified by 1H NMR spectroscopy as the desolvated
thallium salt of high purity (>95%). Ligands 1-methylimidazole
butylimidazole were degassed and stored over 3
A molecular
and 1-
sieves for several days
166
prior to use. Dioxygen (99.994%, BOC Gases) was dried by passing the gas stream
through a column of Drierite. Labeled dioxygen (50% 1802 and 95% 1802) reagents
were purchased from Cambridge Isotope Laboratories, Inc., and used without further
purification. All other reagents were procured from commercial sources and used as
received unless otherwise noted. THF, benzene, toluene, pentane, and Et20 were
distilled from sodium benzophenone ketyl under nitrogen. Dichloromethane, 1,2dichloroethane, and pyridine were distilled from CaH2 under nitrogen. The NMR
solvent CD 2C12 was degassed, passed through activated basic alumina, and stored
over 3
A
molecular sieves prior to use. All air sensitive manipulations were carried
out either in a nitrogen filled Vacuum Atmospheres drybox or by standard Schlenk
line techniques at room temperature unless otherwise noted.
Synthesis. [Fe(XDK)(py)2] (4). To a rapidly stirred suspension of T12(XDK) (2.00
g, 2.02 mmol) and pyridine (1.64 ml, 20.2 mmol) in THF (15 mL) was added a
solution of FeBr2 (446 mg, 2.02 mmol) in THF (5 mL). After 6 h, the precipitated TlBr
was removed by filtration through Celite, and the filtrate was evaporated to dryness.
The crude residue was washed with pentane (20 mL) to remove any residual
pyridine, isolated by filtration, and dried fully in vacuo to afford 4 as a light yellow
powder (1.44 g, 90%). This crude material was used for subsequent reactions without
further purification. Recrystallization from CH 2 C12 /pyridine/Et20 afforded 4 as
yellow blocks which appeared suitable for X-ray crystallography: IR (KBr) 3068, 2961,
2929, 1735, 1696, 1602, 1404, 1463, 1358, 1334, 1218, 1195, 1087, 1039, 958, 835, 760, 626
cm- 1; UV-vis (CH 2 C12 ) (Xmax, nm (E, M- 1 , cm- 1)) 364 (580). Anal. Calcd for
C4 2H 48N 40 8Fel: C, 63.64; H, 6.10; N, 7.07. Found: C, 61.33; H, 6.26; N, 6.60.
[Fe(BXDK)(py)21 (5). This compound was prepared as a light yellow powder
from T12 (BXDK) (2.33 g, 1.61 mmol), pyridine (560 p1, 6.92 mmol), and FeBr 2 (354 mg,
1.61 mmol) by a procedure analogous to that used to prepare 4 (1.55 g, 77%). The
crude material was used for all subsequent reactions. Recrystallization from
167
CH 2C12 /Et 20 provided 5 as opaque yellow needles. IR (KBr) 3062, 3027, 2921, 2857,
1734, 1693, 1603, 1495, 1446, 1352, 1191, 1040, 935, 761, 700, 593, 526 cm- 1; UV-vis
(CH 2C12) (Xmax, nm (E,M- 1, cm-1)) 361 (690). Anal. Calcd for C78H 72N408Fel: C, 74.97;
H, 5.81; N, 4.49. Found: C, 74.45; H, 5.80; N, 4.34.
[Fe 2 (BXDK)(-O
2Ct-Bu)(O 2Ct-Bu)(py) 2]
(6). To a stirred solution of T10 2Ct-Bu
(147 mg, 0.480 mmol) and pyridine (116 p1, 1.44 mmol) in THF (3 mL) was added
FeBr 2 (53 mg, 0.24 mmol) in THF (1 ml). After 10 min this mixture was added in one
portion to a stirred solution of 5 (300 mg, 0.240 mmol) in CH 2C1 2 (3 mL). The
resulting mixture was allowed to stir for 0.5 h, after which time the precipitated TlBr
was removed by filtration through Celite, and the volatile components were
removed in vacuo. Recrystallization from CH 2 C12 /Et 20 afforded 6 as yellow blocks
(265 mg, 73%) which appeared suitable for X-ray crystallography. IR (KBr) 3062, 3028,
2959, 2923, 2863, 1734, 1693, 1602, 1541, 1486, 1407, 1365, 1221, 1189, 1042, 937, 763, 701,
608, 528 cm-1; UV-vis (CH 2C12) (Xmax, nm (E, M-1, cm-1)) 355 (920). Anal. Calcd for
C88 .5H 91N 4 0 12Fe 2C1 (6-0.5CH 2C1 2): C, 68.71; H, 5.90; N, 3.60. Found: C, 68.45; H, 6.06;
N, 3.48. One lattice dichloromethane was identified by X-ray crystallography, and
apparently it was not removed completely by pumping on the sample in vacuo for
one day. When this procedure was repeated with heating, sample decomposition
was observed.
[Fe2(XDK) (g-O 2CPhCy)(O 2CPhCy)(py)2] (7). This compound was prepared from
TI(O 2CPhCy) (308 mg, 0.757 mmol), pyridine (184 L1, 2.27 mmol), FeBr2 (83 mg, 0.378
mmol) and 4 (300 mg, 0.378 mmol) as described for 6. Recrystallization from
benzene/pentane afforded 7 as pale yellow blocks which appeared suitable for X-ray
crystallography (291 mg, 61%). IR (KBr) 3063, 2960, 2928, 2862, 1737, 1699, 1614, 1448,
1405, 1355, 1221, 1187, 1069, 957, 851, 760, 698, 637 cm-1; UV-vis (CH 2C12) ( max, nm (E,
M -1, cm-1)) 354 (840). Anal. Calcd for C68 H 78 N 4 0
Found: C, 64.09; H, 6.63; N, 4.08.
12 Fe 2 :
C, 65.08; H, 6.26; N, 4.46.
168
[Fe 2 (XDK)(g-O 2CAr)(O 2 CAr)(py) 2] (8). This compound was prepared from
T10 2 CAr (342 mg, 0.757 mmol), pyridine (184
l, 2.27 mmol), FeBr 2 (83 mg, 0.378
mmol), and 4 (300 mg, 0.378 mmol) as described for 6. Recrystallization from
THF/pentane provided 8 as yellow blocks (285 mg, 56%). IR (KBr) 2960, 2870, 1736,
1699, 1611, 1536, 1464, 1412, 1357, 1220, 1192, 1069, 958, 841, 760, 698, 511 cm- 1; UV-vis
(CH 2C12 ) (Xmax, nm (E,M-1, cm-1)) 353 (790). Anal. Calcd for C72H 96N 4 0 12 Fe 2 : C, 65.45;
H, 7.32; N, 4.24. Found: C, 66.17; H, 7.01; N, 3.80.
[Fe 2 (XDK)(-O
2 CAr)(O 2 CAr)(3-Fpy) 2]
(9). This compound was prepared from
T10 2CAr (342 mg, 0.757 mmol), 3-fluoropyridine (157 1, 1.82 mmol), FeBr 2 (83 mg,
0.378 mmol), and 4 (300 mg, 0.378 mmol) as described for 6. Recrystallization from
THF/pentane provided 9 as yellow blocks (246 mg, 48%). IR (KBr) 2962, 2931, 2870,
1735, 1697, 1608, 1463, 1409, 1359, 1233, 1197, 1101, 959, 761, 537 cm-1; UV-vis (CH 2C12 )
(Xmax, nm (E, M-1, cm-1)) 361 (790). Anal. Calcd for C7 2H 9 6N 40 12Fe 2F2 : C, 63.72; H,
6.98; N, 4.13. Found: C, 63.95; H, 6.96; N, 3.53.
[Fe 2 (BXDK)(-O
2 Ci-Pr)(O 2Ci-Pr)(py)2]
(10). This compound was prepared from
T10 2 i-Pr (70 mg, 0.24 mmol), pyridine (60 .l, 0.72 mmol), FeBr2 (26 mg, 0.12 mmol),
and 5 (150 mg, 0.120 mmol) as described for 6. Recrystallization from THF/pentane
provided 10 as yellow needles (135 mg, 76%). IR (KBr) 3062, 3028, 2965, 2923, 2869,
1733, 1693, 1602, 1546, 1495, 1446, 1364, 1190, 1034, 850, 763, 701, 528 cm-1; UV-vis
(CH 2C12 ) (Xmax, nm (, M-1, cm-1)) 357 (920). Anal. Calcd for C86H 86 N 40 12Fe 2: C, 69.82;
H, 5.86; N, 3.79. Found: C, 69.34; H, 6.05; N, 3.50.
[Fe 2 (BXDK)(p-O 2 CH 2 t-Bu)(O 2 CH 2 t-Bu)(py)2] (11). This compound was
prepared from T10 2CH 2 t-Bu (77 mg, 0.24 mmol), pyridine (60 l, 0.72 mmol), FeBr2
(26 mg, 0.12 mmol), and 5 (150 mg, 0.120 mmol) as described for 6. Recrystallization
from THF/pentane provided 11 as yellow blocks (130 mg, 71%). IR (KBr) 3062, 3028,
2952, 2866, 1733, 1693, 1603, 1548, 1447, 1364, 1190, 1041, 936, 744, 701, 528 cm-1; UV-vis
169
(CH 2C12) (Xmax, nm (e, M-1, cm-1)) 358 (960). Anal. Calcd for C90H 94 N40
12Fe 2 : C,
70.40;
H, 6.17; N, 3.65. Found: C, 70.20; H, 6.60; N, 3.26.
[Fe 2 (BXDK) (9-O2 CPh)(O2 CPh)(py)2] (12). This compound was prepared from
T10 2 CPh (78 mg, 0.24 mmol), pyridine (60 gi, 0.72 mmol), FeBr 2 (26 mg, 0.12 mmol),
and 5 (150 mg, 0.120 mmol) as described for 6.
Recrystallization
from
THF/CH2Cl 2 /pentane provided 12 as yellow blocks (132 mg, 71%) which appeared
suitable for X-ray crystallography. IR (KBr) 3061, 3028, 2952, 2920, 2865, 1733, 1694,
1604, 1543, 1495, 1447, 1364, 1189, 1069, 1042, 937, 853, 762, 720, 701, 588, 528 cm-1; UVvis (CH 2C12) (Xmax, nm (E,M-1, cm-1)) 351 (1400). Anal. Calcd for C93H 84 N 4 0 12Fe 2C12
(12-1CH 2Cl 2): C, 68.43; H, 5.19; N, 3.43. Found: C, 68.84; H, 5.21; N, 3.13.
[Fe2(BXDK)(J-O 2CPhCy)(O 2 CPhCy)(py)2] (13). This compound was prepared
from T10 2CPhCy (391 mg, 0.960 mmol), pyridine (233 g1, 2.88 mmol), FeBr 2 (106 mg,
0.480 mmol), and 5 (600 mg, 0.480 mmol) as described for 6. Recrystallization from
CH2Cl2/THF/pentane provided 13 as yellow blocks (623 mg, 76%) which appeared
suitable for X-ray crystallography. IR (KBr) 3061, 3028, 2920, 2856, 1735, 1696, 1605,
1494, 1452, 1398, 1366, 1191, 1073, 1042, 864, 762, 699, 526 cm-1; UV-vis (CH 2C12 ) (X ax,
nm (E, M-1, cm-1)) 354 (940). Anal. Calcd for C10 4H 102N 40
12Fe 2 : C,
72.98; H, 6.01; N,
3.27. Found: C, 72.73; H, 6.09; N, 3.02.
[Fe 2 (BXDK)(g-O 2CAr)(O 2 CAr)(py) 2] (14). This compound was prepared from
T10 2CAr (108 mg, 0.240 mmol), pyridine (60
1g,0.72 mmol), FeBr 2 (26 mg, 0.12
mmol), and 5 (150 mg, 0.120 mmol) as described for 6. Recrystallization from
benzene/pentane provided 14 as yellow blocks (144 mg, 67%) which appeared
suitable for X-ray crystallography. IR (KBr) 3068, 3028, 2960, 2928, 2868, 1733, 1693,
1605, 1462, 1406, 1362, 1190, 1070, 937, 762, 701, 730, 528 cm- 1; UV-vis (CH 2C12 ) (Xnax,
nm (E,M-1, cm-1)) 352 (870). Anal. Calcd for C108H120N40
3.15. Found: C, 72.96; H, 7.10; N, 3.03.
12Fe 2:
C, 72.96; H, 6.80; N,
170
[Fe 2 (XDK)(p-O 2CPhCy)(O 2CPhCy)(Me-Im) 2] (15). To a stirred suspension of
T12 (XDK) (420 mg, 0.425 mmol) and Me-Im (71 g1, 0.89 mmol) in THF (5 mL) was
added FeBr 2 (187 mg, 0.851 mmol) in THF (2 mL) followed by T10 2CPhCy (347 mg,
0.851 mmol) in THF (2 mL). After 12 h the mixture was allowed to settle and the
majority of the precipitated TlBr was removed by filtration through Celite. The
resulting cloudy filtrate was evaporated to dryness and taken up in benzene.
Filtration through Celite afforded a clear filtrate. The Celite/TlBr filter cakes were
extracted two additional times with THF (5 mL) to obtain additional product. The
combined filtrates were evaporated to dryness to yield a crude white residue. This
material was suspended in pentane (10 mL), and the resulting white powder was
isolated by filtration. Recrystallization from THF/pentane afforded 15 as colorless
needles (386 mg, 72%). IR (KBr) 2959, 2929, 2859, 1734, 1695, 1609, 1535, 1462, 1405,
1357, 1228, 1192, 1087, 958, 852, 762, 697, 628 cm-1 . Anal. Calcd for C66 H 80 N60
12 Fe 2 : C,
62.86; H, 6.39; N, 6.66. Found: C, 62.66; H, 6.79; N, 6.00.
[Fe 2 (PXDK)(t-O 2 CPhCy)(O 2 CPhCy)(Bu-Im) 2 ] (16). This compound was
prepared from T12 (PXDK) (788 mg, 0.682 mmol), Bu-Im (184 pl, 1.40 mmol), FeBr2
(300 mg, 1.36 mmol), and T10 2CPhCy (556 mg, 1.36 mmol) as described for 15.
Recrystallization from Et20/pentane at -30 oC provided 16 as colorless needles (737
mg, 71%). Recrystallization from a highly dilute pentane solution over several days
at room temperature yielded colorless blocks which appeared suitable for X-ray
crystallography. IR (KBr) 3127, 2959, 2872, 1734, 1693, 1612, 1526, 1456, 1371, 1246, 1187,
1109, 948, 828, 763, 697, 660, 574 cm - 1 . Anal. Calcd for C84H11 6 N 6 0
12Fe 2 : C,
66.66; H,
7.72; N, 5.55. Found: C, 65.13; H, 7.81; N, 5.14.
Collection and Reduction of X-ray Data
All crystals were mounted on the tips of quartz fibers with Paratone-N
(Exxon), cooled to low temperature (- -85 'C), and placed on Siemens CCD X-ray
diffraction system controlled by a Pentium-based PC running the SMART software
171
package.3 3 The general procedures for data collection and reduction follow those
reported previously. 34 All structures were solved by use of the direct methods
programs SIR-92 35 or XS, part of the TEXSAN 3 6 and SHELXTL37 program packages,
respectively. Structure refinements were carried out with XL, part of the SHELXTL
program package. 37 All remaining non-hydrogen atoms were located and their
positions refined by a series of least-squares cycles and Fourier syntheses. Hydrogen
atoms were assigned idealized positions and given a thermal parameter 1.2 times
the thermal parameter of the carbon atom to which each was attached. Empirical
absorption corrections were calculated and applied for each structure using
SADABS, part of the SHELXTL program package.3 7
The structure of 7 contains a lattice benzene molecule which was refined at
partial occupancy. Two of the three lattice benzene molecules in the structure of 13
have large thermal parameters. The structure of 12 contains a lattice THF molecule
disordered over two positions, where an inversion center passes through the center
of a carbon-carbon bond. It was refined as a cyclopentane molecule with one of the
carbon atoms at full occupancy, and the occupancy of the other three carbon atoms
was distributed over two positions per atom and refined. The butyl group of one of
the Bu-Im ligands in the structure of 16 is disordered. The occupancy of the carbon
atom f to the imidazole nitrogen was distributed over two positions and refined.
The other carbon atoms of the butyl group were refined at full occupancy.
Pertinent crystallographic information for each complex including refinement residuals is available in Table 3.2. Selected bond distances and angles, as well
as atomic coordinates and equivalent isotropic displacement parameters, are
provided Tables 3.3 and 3.4-3.8, respectively.
Physical Measurements. NMR spectra were recorded on a Varian Unity-300
NMR spectrometer. 1H NMR chemical shifts are reported versus tetramethylsilane
and referenced to the residual solvent peak. FTIR spectra were recorded on a BioRad
172
FTS-135 FTIR spectrometer. Room-temperature UV-vis spectra were recorded on a
Cary 1E spectrophotometer. Low-temperature spectra were recorded on a HP8452A
diode array spectrophotometer using a custom manufactured immersion dewar,
equipped with a 3 mL cell (1 cm pathlength) with quartz windows connected to a
14/20 female joint via a 10 cm long glass tube. A temperature of -77 'C was
maintained with a dry ice/acetone bath and monitored with a Sensortek Model
BAT-12 thermocouple thermometer. Conductivity measurements were carried out
in THF or CH 2C12 with a Fisher Scientific conductivity bridge, model 9-326, outfitted
with a platinum black electrode. Manometric experiments were carried out
according to literature procedure, 3 8 using Vaska's complex or [Fe(Tp 3 , 5 iPr2) 2 (O 2 CCH 2 Ph)]20 as authentic standards, which form 1:1 and 2:1
complex:dioxygen adducts, respectively. Elemental analyses were performed by
Microlytics, South Deerfield, MA.
EPR Spectroscopy. Spectra were recorded at 4.5 K on a Bruker Model 300 ESP
X-band spectrometer operating at 9.47 GHz. Liquid helium temperatures were
maintained with an Oxford Instruments EPR 900 cryostat. For all measurements 1
mM frozen solutions were prepared in 2-methyltetrahydrofuran, a solvent in which
the samples glassed well.
Resonance Raman Spectroscopy. Raman data were acquired by using a
Coherent Innova 90 argon laser with an excitation wavelength of 647.1 nm and 65
mW of power. A 0.6-m single monochromator (1200 grooves/nm grating), with an
entrance slit of 100 gm, and a liquid nitrogen cooled-CCD detector (Princeton
Instruments, Inc.) were used in a standard backscattering configuration. A
holographic notch filter (Kaiser Optical Systems) was used to attenuate Rayleigh
scattering. Spectra of all samples were collected in toluene or CH 2Cl 2 solution at -77
OC
with the same custom-manufactured dewar used to acquire low-temperature
UV-vis spectra. Solute concentrations were made as high as possible depending on
173
the solubility of the reduced sample, -20 mM in the best cases, to ensure an optimal
signal to noise ratio. A total of 1000 scans each with a three second exposure time
were collected for each sample. Raman shifts were calibrated with toluene or CH 2C12
as an internal standard. The data were processed by using CSMA software (Princeton
Instruments, Inc. Version 2.4A) on a Gateway 2000 computer, and the resulting
ASCII files were processed with Kaleidagraph (Abelbeck Software). Spectra are
displayed in Figures 3.13-3.15, and 0-0 and Fe-O stretching frequencies are listed in
Table 3.11.
Miissbauer Spectroscopy. Solid samples were prepared by suspending -0.04
mol of powdered material in Apiezon N grease, and then packing the mixture into a
nylon sample holder. Frozen solution samples of diferrous complexes 13 or 15 were
prepared in THF in a drybox. In each case 1 mL of the -40 mM solution was syringed
into a nylon sample holder, that was then sealed with Apiezon N grease, brought
out of the drybox, and rapidly cooled to 77 K. Peroxo sample 13-02 was prepared in a
round bottom flask at -77 °C by exposing 1 mL of a THF solution of 13 (40 mM) to
excess 02 (1 atm) for 2 h. The sample was quickly transferred (< 5 s) to a nylon
sample holder, immersed in liquid nitrogen, by means of a glass syringe equipped
with a 4 cm stainless steel needle, and precooled to -77 'C. All data were collected at
77 K with a
5 7 Co
source in a Rh matrix at room temperature and fit to Lorentzian
line shapes. Spectra are illustrated in Figures 3.16-3.18, and parameters derived from
fits are listed in Table 3.12.
UV-Vis Kinetics. Experiments were carried out by using the custom dewar
mentioned above. Reduced samples in freshly distilled THF solution, typically 0.5
mM, were loaded in a drybox and the dewar was fitted with a rubber septum. The
apparatus was brought out, placed under a positive N 2 pressure, and cooled to -77 oC
with a dry ice acetone bath. The samples were subjected to an 02 purge at
atmospheric pressure for 5.0 min at a flow rate of 10 standard cubic centimeters per
174
minute (SCCM), maintained with a Matheson Dyna-Blender Model 8280
oxygen/nitrogen constant flow mixing system. Purging for this time length and at
this flow rate resulted in highly reproducible rate constants, thus assuring that the
entire sample solution and vessel headspace were completely purged with the
desired gas mixture. For dioxygen dependent kinetic studies, the mole fraction of 02
was controlled by diluting pure 02 with dinitrogen, while retaining a total flow rate
of 10 SCCM. Oxygen concentrations were calculated using eq 4, where X = mole
fraction of 02, L = Ostwald coefficient (0.245 for THF), P(g) = partial pressure, and
Vo(1) = molar volume. 39 All experiments were carried out under pseudo -first -order
oxygen concentrations, ranging from3.07-15.4 mM, while keeping the initial
X=
P(g) LV()
+1
)(-
(4)
concentration of diferrous complex constant for each run. Scans were acquired at 600
nm and points were taken every 2-10 sec, depending on the rate at which the
reaction proceeded. Reactions were followed to at least four half lives in all cases.
Data were analyzed with Kaleidagraph (Abelbeck Software) and fit to modeldependent equations by using nonlinear least squares regression. In all cases the data
were fit unambiguously to a first order exponential buildup, defined in eq 5, where
At is the absorbance at time t, AA is the change in absorbance during the reaction,
At = A. + (AA)(1 - exp(-k1bst))
(5)
rate = k [Fe 22+][0 2]
(6)
A. is the absorbance at infinite time, and kobs (- kq) is the observed psuedo first
order rate constant. All plots of ln(kobs) vs ln([02]) were linear with a slope close to
1.0, implying that an overall second order rate law applies, eq 6. Second order rate
constants, tabulated in Table 3.13, were derived from the slopes of kobs vs. [021 plots.
175
Standard errors in these rates are based on linear regression analyses of the slopes,
and are reported at the 95% confidence level. Plots of A60 0 vs. time, kv vs. [02], and
ln(kv) vs. ln([02]) for complexes 6, 7, 13, and 14 are illustrated in Figures 3.19-3.22.
Results and Discussion
Preparation and Characterization of [Fe(XDK)(py) 2 ] (4) and [Fe(BXDK)(py) 2 ] (5).
In order to develop an efficient route to a family of diiron(II) complexes
incorporating the XDK ligand system and ancillary carboxylates of variable steric
properties, the synthesis of pure mononuclear precursors in large quantities was
desired. Treatment of T12 (XDK) or T12 (BXDK) with 1 equiv of iron(II) bromide and
excess pyridine provided yellow bis(pyridine) adducts 4 and 5, respectively, in
multigram quantities and high yield (eq 7). An X-ray structural analysis on the XDK
TI2L + 1FeBr 2
L = XDK, BXDK
THF
rt, N2 , -2 TIBr
N-F
N-Fe""O
/ "
0,
'O
[Fe(XDK)(py) 2] (4)
(7)
or
[Fe(BXDK)(py)2] (5)
derivative revealed the iron atom to be coordinated by three XDK oxygen and two
pyridine nitrogen atoms. 40 The structure is essentially identical to that determined
for the Zn(II) analog, 41 with one long XDK Fe-O interaction at 2.326(5) A and the
other two at an average distance of 2.080(3)
A.
In contrast, the analogous reaction
with 1-methyl- or 1-butylimidazole led to a mixture of intractable products, even
when exactly two equivalents were used.
Preparation and Characterization of Dinuclear [Fe 2 (BXDK)(p-O 2 Ct-Bu)(O 2 CtBu)(py)2]
(6), [Fe 2 (XDK)(g-O 2 CPhCy)(O 2 CPhCy)(py) 2 ] (7), [Fe 2 (XDK)(g-
0 2 CAr)(0 2 CAr)(py)2] (8), [Fe 2 (XDK) (p-O 2 CAr)(O 2 CAr)(3-Fpy)21 (9), [Fe 2 (BXDK) (gO 2 Ci-Pr)(O 2 Ci-Pr)(py)2] (10), [Fe 2 (BXDK) (g-O 2 CH 2 t-Bu)(O 2 CH 2 t-Bu)(py)21 (11),
176
[Fe 2 (BXDK)(g-O 2 CPh)(O 2 CPh)(py) 21 (12), [Fe 2 (BXDK)(p-O 2 CPhCy)(O 2 CPhCy)(py)21
(13), [Fe 2 (BXDK)(g-O 2 CAr)(O 2 CAr)(py) 2] (14), [Fe2(XDK)(R-O
2 CPhCy)(O 2 CPhCy)(Me-
Im)2] (15), and [Fe 2 (PXDK)(p-O 2 CPhCy)(O 2 CPhCy)(Bu-Im) 2] (16). The diferrous
bis(pyridine)
complexes 7-14 were conveniently prepared from 4 or 5 and
"[Fe(O2CR)(py)n]", the latter being generated in situ from iron(II) bromide, the
N-Fe
/
"I"
or_5
S4or5
1FeBr2 + 2TI(O2CR)
FOe
Fe'.,,
ex. py
eN
THF/CH2Cl2
Fe
/
00
Fe
(8)
rt, N2, -2 TIBr
6-14
appropriate ancillary carboxylate, and excess pyridine (eq 8). The 3-fluoropyridine
derivative 9 and imidazole adducts 15-16 were prepared in one-pot reactions from
the thallium carboxylic acid reagents, two equiv of iron(II) bromide, and two equiv
of 3-fluoropyridine or 1-alkylimidazole. In the preparation of 15 and 16, removal of
the TlBr precipitate was aided by allowing the reaction mixtures to stand overnight
prior to filtration through Celite. Additional extractions of the resulting Celite/TlBr
filter cake were required to recover substantial quantities of additional product. All
complexes were obtained in high yield and purity following recrystallization at
room temperature. Despite repeated attempts in each case, elemental analysis
samples of 4, 7, 8 and 16 deviated 1-2% from calculated carbon values. It is unclear
whether these complexes have poor combustion properties and/or they contain
minor impurities, but other closely related derivatives have analyzed correctly.
Schematic representations of all complexes 4-16 are provided in Scheme 3.1.
The IR spectra of complexes 7-16 displayed a new C-O stretch at 1605-1615
cm
- 1,
and another centered at 1693 cm - 1 was more intense and broadened compared
to the dithallium(I) and/or mononuclear iron(II) precursors. Both of these
differences are attributed to the two additional carboxylate ligands in the products.
177
The UV-vis spectra of the pyridine adducts 5-14 all exhibited an absorbance at 350360 nm (e = 500-1000 cm-1), tentatively assigned as a metal-to-ligand charge transfer,
which was absent in the colorless 1-alkylimidazole derivatives. Complexes 4-16 are
all non-elctrolytes, so most are soluble in solvents as non-polar as THF. Where
aliphatic groups have been incorporated into the XDK and 1-alkylimidazole ligands,
for example 16, complexes are readily soluble in diethyl ether and cyclopentane.
Because 6, 7, 12-13, and 16 represent the spectrum of steric hindrance and
electronic differences within this series of complexes, X-ray structures were acquired
to ascertain how each ligand component might influence the iron coordination
geometries and dioxygen reactivity. ORTEP and space-filling diagrams are displayed
in Figures 3.3-3.10, and selected bond distances and angles are listed in Table 2.3.
Each structure consists of a four- or five-coordinate iron atom (Fel) ligated by two
syn-syn bidentate bridging XDK oxygen atoms and one or two monodentate bridging
ancillary carboxylate oxygen atoms. 42 The number of latter donor atoms depends on
the choice of N-donor ligand and the steric properties of the XDK and ancillary
carboxylate substituents. The Fe2 atoms in 6 and 12 are best described as distorted
trigonal bipyramidal, whereas those in 7, 13, and 16 are distorted tetrahedral. The
other iron atom (Fel) has a coordinatively saturated octahedral geometry in all
cases, and it is ligated by two syn-syn bidentate bridging XDK carboxylate oxygen
atoms, two symmetric chelating ancillary carboxylate atoms, and a N-donor nitrogen
atom.
The most significant difference in these structures is the orientation of the
bridging ancillary carboxylate ligand relative to the rest of the complex framework.
Five metrical parameters change significantly within the series: Fe2-0402, Fe20401, Fel-0402-Fe2, Fel-0402-C401, Fe2-0401-C401, and Fe2-0402-C401. These
changes are all related to the tilt angle,
t
, of this monodentate bridging carboxylate
ligand toward the center of the complex, as defined in Figure 3.11.42 Within the
178
subset of pyridine complexes 6, 7, and 12-13, a repulsive interaction between the two
ancillary carboxylate substituents decreases t. In complexes 12 and 13, z is also
affected in the same sense by a steric interaction between the bridging ancillary
carboxylate and the XDK benzyl substituents. As the Fe2-0402 distance (B) lengthens
the Fe2-0401 distance (D) shortens, resulting in no change in the Fel-0402 distance
(A) across the series. Similarly, an increase in the Fe2-0401-C401 angle (y) is
accompanied by a decrease in the Fel-0402-Fe2 (0), Fel-0402-C401 (a), and Fe20402-C401 (0) angles. Based on these parameters, the order of increasing steric
repulsion between the carboxylate substituents for this subset of pyridine complexes
is: 12 < 6 < 7 < 13, corresponding to At = -7', proceeding from 12 -- 13. By contrast, '
is much smaller for the butyl-imidazole adduct 16 compared to all the pyridine
adducts, apparently due to the more basic character of the 1-alkylimidazole donor
compared to pyridine which increases the electron density at Fe2, thereby disrupting
the Fe2-0402 interaction entirely. Hence, for 16 these steric and electronic factors
have the combined effect of nearly inducing a complete carboxylate shift4 2 from the
monodentate bridging observed for the pyridine adducts to syn syn bidentate
bridging.
Reactions of the Diferrous Complexes Toward Dioxygen. UV-Vis and
Manometry. As mentioned in the introduction, previous studies revealed the
presence of a short-lived intermediate generated when [Fe2(PXDK)(J-O 2CtertBu)(O2Ctert-Bu)(Me-Im)21 was exposed to excess 02 at -77 'C in THF solution. As an
initial approach toward stabilizing this species, we implemented the more sterically
demanding BXDK ligand, while holding the other steric properties constant, and
changed the N-donor ligand to pyridine. Space-filling diagrams of the previously
reported complex and 6 are displayed in Figure 3.4. From these representations, it is
apparent that the BXDK benzyl substituents proximal to its carboxylate oxygen donor
atoms shroud the iron coordination sites to a greater extent than do PXDK propyl
179
groups. Furthermore, the benzyl substituents appear to enforce a single approach for
02 to the unsaturated metal center along the Fe-Fe vector.
Exposure of 6 to 02 under identical conditions to those previously reported
resulted in a much slower color change to deep midnight blue over the course of 2-3
h. The buildup of this species was monitored by UV-vis spectroscopy, revealing a
broad absorption centered at -580 nm (e ~ 1200 M-l1cm -1, Figure 3.12A). This feature
is characteristic of an iron(III)-peroxo ligand-to-metal charge transfer band, 1,5 and it
immediately suggested that a family of peroxo complexes having steric and
electronic properties similar to 6 could be accessed. The oxygenation is irreversible,
since application of high vacuum/Ar purge cycles to the solution at -77 'C resulted
in no diminution of the charge transfer band. Warming above -65 'C under excess
02 or Ar, or under high vacuum, caused rapid peroxo decomposition within five
minutes, as judged by a color change to light brown. A similar decomposition was
noted if the peroxo solution is allowed to stand at -77 'C for 12-24 h.
The other diiron(II) tetracarboxylate complexes were then screened for their
ability to form stable peroxo complexes, the results of which are summarized in
Table 3.9. The 02 reactions either resulted in rapid decomposition to form roomtemperature stable Fe(III) products, or afforded an intermediate very similar to that
observed for 6. For BXDK derivatives with pyridine, ancillary carboxylate ligands
smaller than pivolate (10-12) reacted with 02 at a similar rate, but none of these
reactions resulted in the buildup of the 580 nm charge-transfer band. The less
sterically encumbering XDK ligand formed stable peroxo adducts when significantly
more hindered
ancillary
carboxylates
were
implemented,
such as
1-
phenylcyclohexyl- (PhCy) or 2,4,6-triisopropyl (Ar) carboxylic acid (7-8, Figure 3.12B).
Similarly, these hindered carboxylates afforded stable peroxo adducts with 3fluoropyridine or 1-alkylimidazole donors (9, 15-16, Figure 3.12C). The rate of peroxo
formation is considerably faster for the 1-alkylimidazole complexes compared to all
180
the pyridine analogs, however, with 15-16 reacting with 02 to completion within
seconds versus 0.25-2 h for 6-14, as judged by UV-vis spectroscopy. The energy and
intensity of the peroxo-to-iron(III) charge transfer band in these derivatives were the
same as for the pyridine analogs. This result is not surprising because other
diiron(III) peroxo complexes with widely varying ligand sets possess essentially an
identical transition. 15 Furthermore, equivalent irreversible 02 binding and thermal
stability behavior was noted for all peroxo derivatives irrespective of their steric and
electronic properties.
Oxygen uptake experiments were carried out on pyridine adduct 13 in CH 2C12,
and 1-butylimidazole adduct 16 in THF and Et 20 (Table 3.10). Vaska's complex and
[FeTp 3,5-iPr 2 (O2CCH 2Ph)] 20 were used as authentic 02 uptake standards in CH 2C12
and the ethereal solvents, respectively. Complexes 13 and 16 consumed 1.0 + 0.1
equivalents of dioxygen, consistent with a discrete diiron(III) peroxide formulation
for each. When the peroxo adducts were allowed to decay by warming to room
temperature, additional 02 consumption was observed for those manometric
experiments carried out in CH 2C12 or THF, whereas no further uptake was noted for
the diethyl ether trials. All of this decay behavior is in stark contrast to that noted for
another diiron(III) peroxo system, 27 where 0.5 equivalents of 02 was released upon
peroxo decay, and suggests that the peroxide ligand is retained in the decomposition
products and/or ligand or solvent oxidation is occurring concomitant with peroxo
decay. A detailed analysis of this chemistry will be discussed elsewhere. 28
The oxygen adducts exhibited the greatest stability toward decomposition in
the least polar solvents, such as THF and toluene. By contrast, dichloromethane
could be utilized with the more sterically demanding pyridine derivatives 7-8 and
13-14, but the peroxo adducts derived from less hindered 6 or the 1-alkylimidazole
derivatives 15-16 were observed to decompose in this solvent within seconds. The
higher dielectric constant 43 of CH 2C12 (9.08) compared to THF (7.58) and toluene
181
(2.379) may lead to fluxional ligand exchange processes in the chlorinated solvent,
possibly involving a carboxylate shift42 of the ancillary donors, which could result in
dissociation of a carboxylate oxygen ligand. The preference for mondentate over
chelating carboxylate ligation is accentuated in increasingly polar media, 4 1,44 and
such a process here could compromise the steric pocket surrounding the peroxide,
leading to bimolecular decay. The highly sterically demanding R substituents in 7-9
and 13-14 may shroud the peroxide sufficiently to prevent decay by this mechanism.
Rapid degradation of the peroxos derived from complexes 15-16 may be due to the
greater basicity of the 1-alkylimidazole ligand compared to pyridine, which may
render the carboxylate donors even more labile. Alternatively, decay of the peroxo
adducts may occur by direct reaction with CH 2C12, since 1,2-dichloroethane is
detected by GC-MS in the solvent mixture upon warming. 2 8 Taken together, this
survey of steric, electronic, and solvent polarity studies demonstrates that oxygen
adducts can be stabilized with this ligand system provided the carboxylate
substituents form a sufficiently hindered array about the peroxide ligand.
EPR and 1H NMR Studies. The peroxo adducts are EPR silent at 4.5 K, a
feature which is consistent with an antiferromagnetically coupled, S = 0 ground
state. Similar to other diiron(III) peroxides, including the sMMO Hperoxo
intermediate, 15 this coupling is most likely mediated by a bridging peroxide.45 ,46 A
1H
NMR spectrum for the peroxo adducts formed in this study was not observed at
-80 °C, however, suggesting low lying paramagnetic excited states are accessed
thermally at higher temperatures, inducing fast relaxation of the ligand protons. By
contrast, a paramagnetically shifted but reasonably sharp 1H NMR spectrum was
observed
for
a
diiron
(III)
peroxo
complex
with
a
hindered
hydrotris(pyrazolyl)borate ligand. 45
Resonance Raman Studies of the Peroxo Adducts. Raman spectra were
acquired for peroxo adducts derived from complexes 6-8, 13-14, and 16 in fluid
182
solution at -77 0C. The results of these experiments are summarized in Table 3.11,
and the spectra acquired for 16-02 are displayed in Figures 3.13-3.14. The pyridine
and 1-butylimidazole derivatives all give rise to a v( 160-
160)
band at 864 cm- 1 in
toluene solution. When 1802 was used to prepare 16-02 this band shifts to 818 cm-1,
in good agreement with the theoretically predicted shift of 50 cm- 1 for a diatomic 00 harmonic oscillator. The peak shifts slightly to 861 cm-1 for 13.1602 in CH 2C12
solution. A v(Fe-O) band was detected at 484 cm -1 for 13-02 in CH 2C12 , but a
negligible shift was noted for this feature upon 1802 substitution. The band was
obscured entirely in toluene solution due to the intense solvent background peaks
in this spectral region. The observed v(O-O) frequencies of 861-864 cm-1 are typical of
diiron(p-1,2-peroxo) complexes. Although these values are 15-40 cm-1 lower than
other complexes with this ligating motif,1,5 they are 50-60 cm
-1
higher in energy
than those reported for mononuclear iron(III) TI2 -peroxo adducts. 1 We therefore
tentatively assign g-1,2-peroxo coordination mode for 13-02 and 16-02.
Raman spectroscopy was also used to measure the exchange of peroxide with
free 02. Such an exchange process could either be a dissociative (eq 9), implying
-1802
[Fe"' 2( 180 2)L(O 2 CR) 2N 2]
+1602
[Fe" 2 L(-O
2 CR)(O 2 CR)N2 1
+1602
[FeI" 2( 18 0 2 )L(O 2CR) 2 N2]
[FeI 2 L(18 0 2)( 16 0 2)(O2 CR) 2N2]
[Fe"'2 (16 0 2 )L(O 2CR) 2 N2 ]
-1802
(9)
[Fe 112 ( 160 2 )L(O 2CR) 2 N2] (10)
reversible 02 binding, or associative, mediated by a bis(0 2) intermediate (eq 10). The
former mechanism is unlikely because 02 is not liberated when a solution of the
peroxo adduct is placed under a dynamic vacuum. A sample of 16.1802 was prepared
by exposing a 20 mM solution of 16 in toluene to ~0.25 atm of excess 1802 for 1 h, and
Raman spectra were recorded prior to and following a vigorous, five-minute 1602
purge. The v(1 60-
160)
feature appeared in the spectrum immediately following the
purge, but not at the expense of the intensity of the v( 180-
180)
band. Moreover, the
183
v(1 6 0-
16 0)
peak continued to grow in intensity when the solution was allowed to
stir under 1 atm of 1602 over two hours, but again the v( 18 0-
1 8 0)
band did not
diminish. These results suggest that oxygenation of the reduced complex is slow
under the concentrated conditions of the Raman experiment, and that peroxide does
not exchange with free 02 by any mechanism, at least over several hours.
We attempted to obtain structural information about the orientation of
peroxide binding by carrying out a labeling experiment with a 1:2:1 statistical
mixture of 1802, 160180, and 1602 (Figure 3.15). If the peroxide oxygen atoms are
distributed asymmetrically about the Fe(III) ions, then two 160180 peroxide peaks
should be observed, with a 1:1:1:1 relative intensity ratio for the 1802, 160180,
180160, and 1602 isotopomers. Alternatively, equivalent 160180 and 180160 peroxide
stretching frequencies would give rise to three peaks in a 1:2:1 ratio. Interpretation of
resulting Raman spectrum proved to be difficult, however, because of the difficulty
of resolving the 160180 peroxide peak(s) and the fact that their intensity relative to
the 1802 and 1602 bands were obscured by a coincidental toluene peak, even after
considerable effort was expended to subtract the solvent background.
Mossbauer Spectroscopy. Zero-field M6ssbauer studies were carried out to
gain additional information concerning the iron environments in the reduced and
peroxo complexes. The results of these experiments are summarized in Table 3.12,
and spectra with overlaid fits are illustrated in Figures 3.16-3.18. Spectra were
recorded for 13 in the solid state, and for 13 and 15 in frozen THF solution. Each
spectrum consists of two overlapping quadrupole doublets of equal intensity,
indicating inequivalent iron sites. Pairing of the four peaks derived from a fitting
protocol is ambiguous, so both combinations for each complex are listed in Table
3.12. Consistent with our previous assignments in similar complexes, 2 5 we
tentatively attribute the doublet with the higher quadrupole splitting parameter
(AEQ) to the four-coordinate iron(II) center, since it has a more asymmetric
184
coordination environment compared to the octahedral metal ion. The iron(II)
isomer shifts (8) and AEQ values for 13 are slightly different in the solid state and
solution, in contrast to the previous study where a less hindered analog exhibited
the nearly identical parameters in the two different phases. 25 In the present system it
is neither known how the solid and solution structures differ nor what magnitude
of change would be required to yield slightly altered M6ssbauer spectra.
Nevertheless, the equal integrated intensity of the two quadrupole doublets is
consistent with the dinuclear structure remaining intact in solution.
A Mdssbauer spectrum of 13-02 in THF is displayed in Figure 3.18. A modest
amount (20%) of the diiron(II) starting material is apparent in this sample, as judged
by the identical isomer shift of the most positive feature compared to that observed
for 13 (Figure 3.18, Top). This result is consistent with the Raman experiment
mentioned above, where it was determined that oxygenation of extremely
concentrated diiron(II) samples (20 mM) is slow relative to the rate in more dilute
solutions, such as that used for the UV-vis protocol. It is difficult to know a priori
how long to permit the reduced complexes to react with 02 before quenching the
sample in liquid nitrogen. Given the thermal instability of the peroxo complexes,
which decompose significantly within 12-24 h at -77 °C, and the fact that the
spectroscopic properties of the reduced complexes are well known, we chose not to
allow any of these concentrated reactions to proceed beyond -2 h. The bottom
portion of Figure 3.18 displays the experimental data with the dirion(II) component
subtracted out, together with a fit of the peroxo spectrum.
Like the iron(II) complexes, the peroxo consists of two overlapping
quadrupole doublets of equal integrated intensity. Both possible pairings of the four
simulated peaks are listed in Table 3.12, along with the M6ssbauer parameters for
oxyhemerythrin 47 and MMO-Hperoxo . 15 The isomer shifts and AEQ values are both
in the range typical of high spin Fe(III), 48 and these parameters bear considerable
185
resemblance to those determined for the phenoxo-bridged peroxo complex in Table
3.1. 2 1 These results indicate either that the peroxo sample is composed of one
dinuclear complex with inequivalent iron centers, or of two different dinuclear
peroxo complexes with equivalent iron centers within the same molecule. Since a
1:1 ratio of two different peroxo isomers is highly improbable, we conclude the
former alternative best describes the makeup of 13-02.
Kinetic Studies of the Reaction of the Diferrous Complexes With 02 and a
Proposed Mechanism for Peroxo Formation. The UV-vis, manometric, EPR,
resonance Raman, and M6ssbauer spectroscopic data collectively point to the
formation of a discrete (g-1,2-peroxo) diiron(III) complex with inequivalent metal
centers. With these results in hand, we decided to investigate the mechanism of
peroxo formation by time-resolved UV-vis kinetic studies to determine the reaction
order with respect to the diferrous complex and 02. Moreover, X-ray structural
investigations demonstrated that the coordination number of one of the starting
diiron(II) centers could be modulated as a function of intramolecular steric
repulsions (vide supra), and we were interested to determine whether this effect
might play a role in the kinetics of oxygenation.
Kinetic runs were carried out at -77 'C on pyridine adducts 6, 7, 13, and 14
using a custom-made immersion dewar. All experiments were performed under
pseudo-first-order conditions, with the iron complex as the limiting reagent.
Dioxygen concentrations were varied over a range of 3.1-15.4 mM. The buildup of
the peroxo charge transfer band was monitored at 600 nm as a function of time
(Figures 3.19-3.22, Top). These plots could be fit to a first order exponential buildup
for each complex. Plots of ln(kv) vs. the ln[02] afforded straight lines with slopes
near 1.0, indicating that the oxygenation reaction is first order in this reagent
(Figures 3.19-3.22, Bottom). Second order rate constants were obtained for the four
iron complexes from the slopes derived from plots of kv vs. the [02] (Figures 3.19-
186
3.22, Middle). These rate constants are provided in Table 3.13 along with metrical
data from the crystal structures of 6, 7, and 13 describing the orientation of each
bridging ancillary carboxylate. Activation parameters could not be obtained because
the peroxo adducts decompose quite rapidly above -65 'C, thus limiting the
temperature for aquisition to only a 150 range.
The first-order dependence in each reagent indicates that the rate limiting
step in these oxygenation reactions is a bimolecular collision between the diiron(II)
complex and dioxygen. Within the series, the rate constants increase modestly over
a four-fold range as the steric demands of the carboxylate substituents are enhanced.
This kinetic trend correlates well with lengthening of the Fe2-0402 bond and
decrease in r as a function of the same steric parameters and may indicate that, in
the transition state, cleavage of this bond is required to open a coordination site for
02 binding to Fe2. This event corresponds to a rate limiting carboxylate shift from
mondentate bridging to syn syn bidentate bridging. Such structural/kinetic
comparisons must be viewed with caution, however, since the M6ssbauer studies
on the diiron(II) complexes showed that the solid and solution structures may not
be identical. Nevertheless, the trend does suggest that bond cleavage is involved in
the rate limiting step and argues against a mechanism where passage of the 02
molecule to an iron center is impeded by the sterically encumbering carboxylate
substituents. The latter mechanism was observed for the oxygenation of a series of
iron(II) hydrotris(pyrazolyl)borate-carboxylate complexes, where exceedingly bulky
carboxylate substituents shut down the reaction entirely. 45 By contrast, space-filling
models of 6-16 show that the pathway to the four- or five-coordinate iron center is
unobstructed, regardless of the carboxylate substituents (Figures 3.4 and 3.6, for
example).
The 1-alkylimidazole adducts 15 and 16 react to completion with 02 in the
time of mixing of the two reagents (< 1 s), much more rapidly than the oxygenation
187
rates observed for the pyridine complexes. Neither could be studied by these
conventional kinetics methods. The less hindered analog [Fe2(PXDK)(R-O 2 CtertBu)(0 2 Ctert-Bu)(Me-Im)2], was previously analyzed by stopped-flow UV-vis
spectroscopy under very similar experimental conditions: [Fe 22 +] = 0.8 mM (after
mixing) in THF, T = -76 'C, excess 02.25 These studies revealed a pseudo-first-order
rate constant of 300 s- 1, a value > 105 faster than the pseudo-first-order rate constants
observed for the pyridine adducts. The dramatically enhanced rates could be due in
part to the minimal bonding interaction between the Fe2 and 0402 in this complex.
Because changes in this parameter have only a modest effect on the rate constants,
however, we attribute most of the rate difference instead to the greater basicity of the
1-alkylimidazole ligand compared with pyridine. This electronic factor should lead
to a significantly more negative midpoint potential for the diiron(II)/diron(III)
couple with 1-alkylimidazole, thereby enhancing the thermodynamic driving force
for the 02 reaction, and consequently accelerating the rate.
A mechanism for peroxo formation is presented in Scheme 3.2. Although
peroxo buildup exhibits clean first order dependence in each reaction component,
the kinetics do not reveal if the rate limiting event leads to peroxo formation
directly. Alternatively, very fast electron transfer and/or ligand rearrangement steps
may occur after 02 binding, thereby preceding final peroxo assembly. Consequently,
if the final peroxo formation event is beyond the rate limiting step, then prior
intermediates could involve a diiron(II)-02 adduct, an Fe(II)Fe(III) superoxide
complex, and/or several plausible isomers based on the arrangement of the
carboxylate and nitrogen donors. Two likely possibilities are structures a and b in
Scheme 3.2. For the final structure, the spectroscopic data are consistent with a
bridged peroxo arrangement with inequivalent iron sites. To accommodate the
latter feature, the mirror plane and rotational symmetry of the diiron-XDK
framework must be removed. Structures c-e incorporate these properties through
188
the orientation of the peroxide (c) or the other ligands (d and e). We consider these
or closely related isomers as viable candidates for the structures of the peroxo
complexes presented here.
Conclusions
A family of diferric peroxo-bridged complexes has been prepared which
matches exactly the combination of carboxylate and imidazole donors of the Hperoxo
intermediate in sMMO. A variety of methods including UV-Vis, EPR, Resonance
Raman, and M6ssbauer spectroscopies have been employed to elucidate their
structures. These adducts have inequivalent iron coordination environments, a
feature which is attributed either to an asymmetric peroxide bridge, a
disproportionate arrangement of the ancillary carboxylate and nitrogen donor
ligands about each iron center, or a combination of two. Kinetic studies revealed
that the rate of peroxo formation is first order in diiron(II) complex and 02,
implicating
a rate-determining bimolecular
collision between the reaction
components. Moreover, the rate of peroxo formation tracks inversely with the steric
demands of the carboxylate substituents, implying that a carboxylate shift is
associated with the rate-determining step. The oxygenation rate is affected much
more dramatically by the basicity of the N-donor ligand, however, with a difference
of >105 s- 1 noted for the pseudo-first-order rate constants with 1-alkylimidazole
versus pyridine ligation. In sum, these studies have spawned the most accurate
compositional models of the Hperoxo intermediate reported to date, and their steric
and electronic tunability have allowed us to explain many factors which affect their
formation, structure, and stability.
Acknowledgement. This work was supported by a grant from the National
Science Foundation and AKZO Corp. DDL thanks Ann Valentine and Dietrich
189
Steinhuebel of the Lippard group at MIT for experimental assistance and many
helpful discussions.
190
References and Notes
(1)
Feig, A. L.; Lippard, S. J. Chem. Rev. 1994, 94, 759-805.
(2)
Wallar, B. J.; Lipscomb, J. D. Chem. Rev. 1996, 96, 2625-2657.
(3)
Liu, K. E.; Lippard, S. J. In Adv. Inorg. Chem.; A. G. Sykes, Ed.; Academic
Press, Inc.: San Diego, CA, 1995; Vol. 42; pp 263-289.
(4)
Valentine, A. M.; Lippard, S. J. J. Chem. Soc., Dalton Trans. 1997, 3925-3931.
(5)
Que, L., Jr. J. Chem. Soc., Dalton Trans. 1997, 3933-3940.
(6)
Rosenzweig, A. C.; Brandstetter, H.; Whittington, D. A.; Nordlund, P.;
Lippard, S. J.; Frederick, C. A. Proteins1997, 29, 141-152.
(7)
Rosenzweig, A. C.; Nordlund, P.; Takahara, P. M.; Frederick, C. A.; Lippard, S.
J. Chem. Biol. 1995, 2, 409-418.
(8)
Nordlund, P.; Eklund, H. Current Opinion in Structural Biology 1995, 5, 758766.
(9)
Kurtz, D. M. J.JBIC 1997, 2, 159-167.
(10)
Edmundson, D. E.; Huynh, B. H. Inorg. Chim. Acta 1996, 252, 399-404.
(11)
Burdi, D.; Riggs-Gelasco, P.; Tong, W.; Willems, J.-P.; Lee, H.-I.; Doan, P. E.;
Sturgeon, B.; Shu, L.; Que, L., Jr.; Hoffmann, B. M.; Stubbe, J. Stenbock
Symposium Proceedings: Biosynthesis and Function of Metal Clusters For
Enzymes 1997, 25, 85-95.
(12)
Sturgeon, B. E.; Burdi, D.; Chen, S.; Huynh, B. H.; Edmondson, D. E.; Stubbe, J.
J. Am. Chem. Soc. 1997, 118, 7551-7557.
(13)
Willems, J.-P.; Lee, H.-I.; Burdi, D.; Doan, P. E.; Stubbe, J. J. Am. Chem. Soc.
1997, 119, 9816-9824.
(14)
Riggs-Gelasco, P.; Shu, L.; Chen, S.; Burdi, D.; Huyng, B. H.; Que, L., Jr.; Stubbe,
J. J. Am. Chem. Soc. 1998, 120, In Press.
(15)
Liu, K. E.; Valentine, A. M.; Wang, D.; Huynh, B. H.; Edmondson, D. E.;
Salifoglou, A.; Lippard, S. J. J. Am. Chem. Soc. 1995, 117, 10174-10185.
191
(16)
Lee, S.-K.; Nesheim, J. C.; Lipscomb, J. D. J. Biol. Chem. 1993, 268, 21569-21577.
(17)
Shu, L.; Nesheim, J. C.; Kauffmann, K.; Munck, E.; Lipscomb, J. D.; Que, L., Jr.
Science 1997, 275, 515-518.
(18)
Bollinger, J. M. J.; Krebs, C.; Vicol, A.; Chen, S.; Ley, B. A.; Edmondson, D. E.;
Huynh, B. H. J. Am. Chem. Soc. 1998, 120, In Press.
(19)
Valentine, A. M.; Tavares, P.; Pereira, A. S.; Davydov, R.; Krebs, C.; Hoffman,
B. M.; Edmondson, D. E.; Huynh, B. H.; Lippard, S. J. J. Am. Chem. Soc. 1998,
120, In Press.
(20)
Kim, K.; Lippard, S. J. J. Am. Chem. Soc. 1996, 118, 4914-4915.
(21)
Ookubo, T.; Sugimoto, H.; Nagayama, T.; Masuda, H.; Sato, T.; Tanaka, K.;
Maeda, Y.; Okawa, H.; Hayashi, Y.; Uehara, A.; Suzuki, M. J. Am. Chem. Soc.
1996, 118, 701-702.
(22)
Dong, Y.; Yan, S.; V.G. Young, J.; Que, L., Jr. Angew. Chem. Int. Ed. Engl. 1996,
35, 618-620.
(23)
Dong, Y.; Zang, Y. Z.; Shu, L.; Wilkinson, E. C.; Que, L., Jr. J. Am. Chem. Soc.
1997, 119, 12683-12684.
(24)
Que, L., Jr.; Dong, Y. Acc. Chem. Res. 1996, 29, 190-196.
(25)
Herold, S. H.; Lippard, S. J. J. Am. Chem. Soc. 1997, 119, 145-156.
(26)
Feig, A. L.; Masschelein, A.; Bakac, A.; Lippard, S. J. J. Am. Chem. Soc. 1997,
119, 334-342.
(27)
Feig, A. L.; Becker, M.; Schindler, S.; von Eldik, R..; Lippard, S. J. Inorg. Chem.
1996, 35, 2590-2601.
(28)
LeCloux, D. D. Chapter 4.
(29)
Rebek, J., Jr..; Marshall, L.; Wolak, R.; Parris, K.; Killoran, M.; Askew, B.;
Nemeth, D.; Islam, N. J. Am. Chem. Soc. 1985, 107, 7476-7481.
(30)
LeCloux, D. D.; Lippard, S. J. Inorg. Chem. 1997, 36, 4035-4046.
192
(31)
Calderon, S. N.; Newman, A. H.; Tortella, F. C. J. Med. Chem. 1991, 34, 31593164.
(32)
Doyle, G.; Erikson, K. A.; Modrick, M.; Ansell, G. Organometallics 1982, 1,
1613-1618.
(33)
SMART. 4.0; Siemens Industrial Automation, Inc.: Madison, WI, 1994.
(34)
Feig, A. L.; Bautista, M. T.; Lippard, S. J. Inorg. Chem. 1996, 35, 6892-6898.
(35)
Burla, M. C.; Camalli, M.; Cascarano, G.; Giacovazzo, C.; Polidori, G.; Spagna,
R.; Viterbo, D. J. Appl. Crystallogr.1989, 22, 389-393.
(36)
TEXSAN: Single Crystal Structure Analysis Software. 1.6c; Molecular
Structure Corporation: The Woodlands, TX, 1995.
(37)
SHELXTL: Structure Analysis Program.5.0; Siemens Industrial Automation,
Inc.: Madison, WI, 1995.
(38)
Mahapatra, S.; Halfen, J. A.; Wilkinson, E. C.; Pan, G.; Wang, X.; Jr., Young,
V.G., Jr.; Cramer, C. J.; Que, L., Jr..; Tolman, W. B. J. Am. Chem. Soc. 1996, 118,
11555-11574.
(39)
Oxygen and Ozone; R. Battino, Ed.; Pergamon Press: Oxford, U.K., 1981;
Vol. 7.
(40).
X-ray data for 4 crystallized from CH 2 C12 /Et 2 0: P21/n, a = 12.3185(2)
16.2489(2)
A, c = 20.4920 (1) A,
A, b =
3 = 103.77(1)0, V = 3983.92(8) A3, Z = 4, T = 188 K,
R = 6.77%, wR 2 = 13.72%. This structure is not described in further detail here
because it is nearly identical to that of the Zn(II) analog; see reference 41.
(41)
Tanase, T.; Yun, J. W.; Lippard, S. J. Inorg. Chem. 1995, 34, 4220-4229.
(42)
Rardin, R. L.; Tolman, W. B.; Lippard, S. J. New J. Chem. 1991, 15, 417-430.
(43)
Handbook of Chemistry and Physics, 68th Edition; R. C. Weast, Ed.; CRC
Press, Inc.: Boca Raton, FL, 1988.
(44)
Connolly, J. A.; Kim, J. H.; Banaszcyk, M.; Drouin, M.; Chin, J. Inorg. Chem.
1995, 34, 1094.
193
(45)
Kitajima, N.; Tamura, N.; Amagai, H.; Fukui, H.; Moro-oka, Y.; Mizutani, Y.;
Kitagawa, T.; Mathur, R.; Heerwegh, K.; Reed, C. A.; Randall, C. R.; Que, L., Jr.;
Tatsumi, K. J. Am. Chem. Soc. 1994, 116, 9071-9085.
(46)
Dong, Y.; Menage, S.; Brennan, B. A.; Elgren, T. E.; Jang, H. G.; Pearce, L. L.;
Que, L., Jr. J. Am. Chem. Soc. 1993, 115, 1851-1859.
(47)
Clark, P. E.; Webb, J. Biochemistry 1981, 20, 4628-4632.
(48)
Dickson, D. P. E.; Berry, F. J. In Mdssbauer Spectroscopy Cambridge University
Press: Cambridge, U.K., 1986.
Table 3.1. Summary of data acquired for notable RR and sMMO model complexes.
UV-Vis (Xmax, nm
(e, M-1cm- 1 ))
Resonance Raman
(cm-1)
VO-O
VFe- O
Mossbauer
X-ray (A)
(mm/s)
Fe...Fe
0-0
8
AEQ
0.48, 0.08
1.6, 0.5
0.66
1.40
S-73+
R
O
'
R
RR
RO
O R
R'
Not Reported
694 (2650)
888
415
4.007(4)
1.406(8)
500-800 (1700)
Not
Detected
Not
Detected
3.327(2)
1.426(6)
0.58, 0.65 0.74, 1.70
694 (2650)
900
Not
Reported
3.462(2)
1.416(7)
Not Reported
R
N-N
\
N-N,
H-BN-N,..Fe
Fe- O _ . Fe..,N-NB-H
N-N
Not Reported
350(8000)
'N-N
RKR
R = i-Pr, R'= CH2Ph
ref.
Table 3.2. Summary of X-ray Crystallographic Data.
formula
fw
space group
a, A
b, A
c, A
a(,deg
3, deg
y, deg
V, A3
Z
Pcalcd, g /cm 3
T, oC
jt(Mo Ka), mm -1
transmission coeff
20 limits, deg
total no. of data
no. of unique data
observed dataa
no. of parameters
R(%)b
wR 2 (%)c
max, min peaks, e/A
3
6.CH2C12
7-2.5PhH
12-2CH 2C1 2 0.5THF
C89H92N4012
Fe 2 C12
1592.27
P1
13.1316(2)
17.1922(1)
19.0528(1)
96.764(1)
104.042(1)
96.712(1)
4096.30(7)
2
1.291
-85
0.483
0.857-1.000
3-46
17736
11368
9221
982
4.48
10.95
0.656, -0.506
C 8 3 H 9 3 N 4 01 2 Fe 2
C9 6 H 9 0N 4 0
Fe 2 C14
1753.22
P1
14.0207(2)
16.78920(10)
19.3547(3)
96.1947(9)
102.8972(8)
96.2151(9)
4373.79(10)
1450.38
P1
14.7993(3)
15.5674(3)
18.0666(3)
88.8330(10)
81.5630(10)
70.7380(10)
3885.02(13)
2
1.266
-85
0.437
0.788-1.000
3-57
22684
16152
13216
897
4.59
12.94
1.046, -0.385
1.331
-85
0.518
0.858-1.000
3-57
25335
17952
13809
1025
8.81
25.18
1.247, -1.533
aObservation criterion: I > 2cy(I). b R = ZI IFo I -IFc I I /I IFo I. CwR
2
1 2 .5
13.3PhH
16
C1 2 2 H120N4012
Fe2
1945.92
P21/n
21.1197(11)
17.9106(9)
27.8373(14)
10233.4(9)
C84 H11 6 N6012
Fe2
1513.53
P1
13.2699(2)
14.09470(10)
23.0607(4)
97.1800(10)
97.3300(10)
106.4840(10)
4042.74(10)
1.263
-85
0.349
0.791-1.000
3-57
40431
14536
9120
1231
7.52
15.56
0.752, -0.361
1.243
-85
0.422
0.871-1.000
3-57
25104
17409
12887
937
5.18
12.99
1.056, -0.597
103.6300(10)
= {[w(Fo2-Fc2 ) 2 ]/Y[w(Fo 2 ) 2 ]}1 / 2 .
196
Table 3.3. Selected Bond Distances and Angles.a
V
Distances (A)
Angles (deg)
Fel-..Fe2
Fel-0101
3.5110(6)
0101-Fel-0201
103.67(9)
2.091(2)
0101-Fel-0501
163.63(9)
Fel-0201
Fel-0402
2.077(2)
2.172(2)
0101-Fel-N501
0402-Fel-N501
91.90(10)
174.12(10)
Fel-0502
2.193(2)
0501-Fel-0502
60.10(9)
Fel-N501
2.191(3)
0102-Fe2-0202
133.33(9)
Fe2-0102
Fe2-0202
0102-Fe2-0401
0401-Fe2-N401
118.34(9)
105.20(9)
Fe2-0401
1.992(2)
2.017(2)
2.062(2)
Fel-0402-Fe2
102.13(9)
Fe2-N401
2.096(2)
170.6(2)
Fe2-0402
2.340(2)
Fel-0402-C401
Fe2-0401-C401
97.5(2)
Fe2-0402-C401
84.5(2)
Fel...Fe2
Fel-0101
3.5932(4)
2.064(2)
0101-Fel-0201
104.50(7)
0101-Fel-0501
161.68(7)
Fel-0201
Fel-0402
2.095(2)
0101-Fel-N501
84.89(7)
2.217(2)
0402-Fel-N501
170.97(7)
Fel-0502
2.221(2)
0501-Fel-0502
60.18(6)
Fel-N501
2.182(2)
0102-Fe2-0202
135.53(7)
Fe2-0102
Fe2-0202
Fe2-0401
0102-Fe2-0401
0401-Fe2-N401
Fel-0402-Fe2
Fel-0402-C401
Fe2-0401-C401
Fe2-0402-C401
104.81(7)
108.02(6)
100.47(6)
Fe2-N401
Fe2..-O402
2.000(2)
1.979(2)
2.050(2)
2.115(2)
2.454(2)
Fel.--Fe2
Fel-0101
3.5121(8)
2.091(3)
0101-Fel-0201
109.65(13)
0101-Fel-0501
149.96(13)
Fel-0201
Fel-0402
2.070(3)
0101-Fel-N501
90.39(12)
2.184(3)
0402-Fel-N501
174.99(14)
Fel-0502
2.104(4)
0501-Fel-0502
59.43(13)
Fel-N501
2.145(3)
0102-Fe2-0202
123.72(14)
171.5(2)
100.15(13)
81.84(12)
197
Table 3.3. (cont 'd) Selected Bond Distances and Angles.a
Distances
16
Angles
Fe2-0102
2.006(3)
0102-Fe2-0401
102.5(2)
Fe2-0202
1.990(3)
0401-Fe2-N401
Fe2-0401
2.047(4)
Fel-0402-Fe2
97.1(2)
102.55(12)
Fe2-N401
2.093(3)
Fel-0402-C401
168.9(3)
Fe2-0402
2.317(3)
Fe2-0401-C401
96.3(3)
Fe2-0402-C401
84.6(3)
Fel.-.Fe2
3.5649(10)
0101-Fel-0201
Fel-0101
2.077(3)
0101-Fel-0501
105.84(13)
161.74(14)
Fel-0201
2.110(3)
0101-Fel-N501
83.06(14)
Fel-0402
2.194(4)
0402-Fel-N501
170.47(14)
Fel-0502
2.203(3)
0501-Fel-0502
60.24(13)
Fel-N501
Fe2-0102
2.174(4)
0102-Fe2-0202
133.4(2)
1.970(3)
0102-Fe2-0401
Fe2-0202
1.986(3)
0401-Fe2-N401
107.5(2)
106.0(2)
Fe2-0401
2.017(4)
Fel-0402-Fe2
98.96(13)
Fe2-N401
2.089(4)
Fel-0402-C401
168.0(3)
Fe2.--O402
2.489(4)
Fe2-0401-C401
101.5(3)
Fe2-0402-C401
80.3(3)
Fel...Fe2
Fel-0101
Fel-0201
Fel-0402
Fel-0502
Fel-N501
3.6671(5)
2.064(2)
2.117(2)
2.154(2)
2.305(2)
2.148(2)
0101-Fel-0201
0101-Fel-0501
0101-Fel-N501
0402-Fel-N501
0501-Fel-0502
0102-Fe2-0202
92.72(8)
156.53(8)
86.82(8)
174.34(8)
59.45(7)
146.36(7)
Fe2-0102
2.026(2)
0102-Fe2-0401
100.01(8)
Fe2-0202
Fe2-0401
1.974(2)
0401-Fe2-N401
106.03(8)
2.006(4)
Fel-0402-Fe2
87.72(6)
Fe2-N401
Fe2*.. 402
2.072(2)
3.055(2)
Fel-0402-C401
Fe2-0401-C401
152.6(2)
116.6(2)
198
Table 3.3. (cont ' d) Selected Bond Distances and Angles.a
Distances
Angles
Fe2-0402-C401
67.46(15)
aNumbers in parentheses are estimated standard deviations of the last significant
figure. Atoms are labeled as indicated in Figures 3.3-3.10.
199
Table 3.4. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A 2 x 103) for 6. a
atom
Fe(2)
Fe(1)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
N(401)
N(501)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(119)
C(120)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(127)
C(128)
x
1548(1)
818(1)
-16(2)
455(2)
-2847(2)
-1246(2)
614(2)
1540(2)
-71(2)
-1656(2)
3116(2)
2189(2)
1764(2)
1364(2)
-2089(2)
-903(2)
1405(2)
-615(2)
13(2)
-2513(2)
-1625(2)
375(2)
-1692(2)
-3504(2)
-466(2)
-630(2)
-1650(2)
-2606(2)
-2529(2)
-1513(2)
1274(2)
1237(3)
2015(4)
2829(4)
2896(3)
2118(3)
-2646(3)
-2567(3)
-3425(4)
-4380(4)
-4483(3)
-3612 (3)
-4564(2)
-5147(3)
-6096(3)
-6464(3)
y
1050(1)
2144(1)
991(1)
303(1)
815(1)
-603(1)
2550(1)
2119(1)
2167(1)
3105(1)
1096(1)
1657(1)
3265(1)
2309(1)
84(1)
2663(1)
439(1)
2643(2)
356(2)
202(2)
-580(2)
-567(2)
-2047(2)
-461(2)
-422(2)
-1141(2)
-1247(2)
-1244(2)
-462(2)
-343(2)
-976(2)
-1786(2)
-2188(3)
-1803(3)
-1006(3)
-594(2)
-2305(2)
-2225(2)
-2473(2)
-2798(3)
-2893(2)
-2647 (2)
-741(2)
-224(2)
-503(3)
-1298(3)
z
U(eq)
7589(1)
9015(1)
8745(1)
7836(1)
7813(1)
6356(1)
8013(1)
7253(1)
5611(1)
7333(1)
8144(1)
8809(1)
9613(1)
10213(1)
7073(1)
6438(1)
6542(1)
9103(2)
8359(2)
7680(2)
6874(2)
9265(2)
6845(2)
8469(2)
8561(2)
7959(2)
7334(2)
7647(2)
8137(2)
8774(2)
9116(2)
9152(2)
8980(3)
8766(3)
8740(2)
8922(2)
6195(2)
5490(2)
4891(2)
4982(3)
5673(3)
6279(2)
7920(2)
7552(2)
7021(2)
6854(2)
26(1)
29(1)
33(1)
29(1)
34(1)
30(1)
35(1)
35(1)
31(1)
37(1)
41(1)
38(1)
50(1)
48(1)
24(1)
24(1)
28(1)
41(1)
25(1)
26(1)
23(1)
32(1)
31(1)
33(1)
25(1)
25(1)
25(1)
27(1)
25(1)
27(1)
34(1)
51(1)
71(1)
72(1)
65(1)
47(1)
36(1)
45(1)
62(1)
69(1)
62(1)
47(1)
34(1)
44(1)
57(1)
60(1)
200
Table 3.4.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 6. a
atom
C(129)
C(130)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(219)
C(220)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
C(227)
C(228)
C(229)
C(230)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
x
-5911(3)
-4976(3)
1174(2)
-1012(2)
-164(2)
2642(3)
748(2)
-879(3)
1503(2)
1576(2)
501(2)
-88(2)
-304(2)
763(3)
3169(3)
3049(3)
3511(5)
4097(5)
4234(4)
3778(3)
-160(2)
-891(3)
-1675(3)
-1725(3)
-1015(3)
-245(3)
-1854(3)
-1770(3)
-2660(5)
-3653(5)
-3750(4)
-2852(3)
-1492(2)
-1643(2)
-2494(2)
-3183(2)
-3059(2)
-2209(2)
-2667(3)
-3836(2)
3076(2)
4069(3)
4973(4)
3845(4)
4384(4)
1665(3)
y
-1821(2)
-1546(2)
2663(2)
3249(2)
2731(2)
3732(2)
3659(2)
4706(2)
3515(2)
3566(2)
3543(2)
4183(2)
4049(2)
4072(2)
4571(2)
5141(3)
5929(3)
6144(3)
5594(3)
4804(2)
3559(2)
4090(2)
3998(2)
3393(2)
2865(2)
2946(2)
4873(2)
5423(2)
5570(3)
5181(3)
4646(3)
4491(2)
1365(2)
1928(2)
1812(2)
1102(2)
515(2)
670(2)
2434(2)
-244(2)
1482(2)
1725(2)
1320(4)
1545(4)
2611(3)
818(2)
z
7214(2)
7749(2)
7579(2)
6991(2)
6023(2)
8008(2)
5368(2)
7395(2)
7463(2)
6679(2)
6109(2)
6373(2)
7101(2)
7675(2)
8087(2)
8639(3)
8704(4)
8240(5)
7707(4)
7631(3)
4685(2)
4573(2)
3913(2)
3358(2)
3469(2)
4122(2)
6864(2)
6395(2)
5897(3)
5877(3)
6352(4)
6843(3)
6741(2)
6277(2)
5659(2)
5511(2)
5960(2)
6580(2)
5159(2)
5786(2)
8739(2)
9365(2)
9201(3)
10053(2)
9410(3)
6019(2)
U(eq)
57(1)
44(1)
30(1)
28(1)
25(1)
39(1)
29(1)
38(1)
31(1)
29(1)
27(1)
29(1)
30(1)
35(1)
47(1)
73(1)
102(2)
107(3)
93(2)
61(1)
33(1)
40(1)
49(1)
54(1)
55(1)
43(1)
41(1)
55(1)
80(2)
98(2)
91(2)
63(1)
24(1)
24(1)
27(1)
32(1)
29(1)
25(1)
40(1)
41(1)
33(1)
42(1)
100(2)
97(2)
106(2)
40(1)
201
Table 3.4.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 6.a
atom
C(407)
C(408)
C(409)
C(410)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
C(509)
C(510)
C(601)
Cl(1)
C1(2)
x
1600(3)
1241(3)
989(3)
1082(2)
1772(3)
2230(4)
1314(6)
2911(5)
2923(6)
-601(4)
-1482(5)
-2435(4)
-2465(4)
-1529(3)
-4194(4)
-5214(1)
-4667(1)
y
440(2)
-358(2)
-754(2)
-341(2)
3012(2)
3577(2)
3804(5)
4309(3)
3169(3)
3425(2)
3769(3)
3298(4)
2507(3)
2205(3)
2146(3)
1421(1)
2961(1)
z
5330(2)
5158(2)
5688(2)
6369(2)
10209(2)
10932(2)
11190(5)
10826(3)
11469(3)
9237(3)
9279(3)
9168(3)
9023(3)
8996(3)
7030(4)
6505(1)
7422(1)
U(eq)
47(1)
39(1)
40(1)
34(1)
45(1)
56(1)
194(5)
95(2)
125(3)
67(1)
90(2)
87(2)
94(2)
64(1)
104(2)
109(1)
113(1)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
202
Table 3.5. Atomic coordinates (x 10 4 ) and equivalent
isotropic displacement parameters (A2 x 10 3 ) for 7. a
atom
Fe (1)
Fe(2)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
N(401)
N(501)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(301)
C(302)
C(303)
C(304)
x
-2350(1)
-2689(1)
-2162(1)
-2176(1)
-3811(1)
-3650(1)
-3696(1)
-3769(1)
-5805(1)
-6048(1)
-1487(1)
-1675(1)
-2101(1)
-1033(1)
-3710(1)
-5820(1)
-3346(1)
-3022(1)
-1959(1)
-3362(2)
-3270(2)
-292(2)
-2253(2)
-2496(2)
-1342(2)
-1439(2)
-2337(2)
-2362(2)
-2442(2)
-1543(2)
-4002(1)
-6040(2)
-5919(2)
-3927(2)
-6726(2)
-6885(2)
-4661(2)
-5267(2)
-6187 (2)
-6811(2)
-6268(2)
-5314(2)
-4767(2)
-5684(2)
-6505(2)
-6368(2)
y
6383(1)
5997(1)
5061(1)
4733(1)
4196(1)
3501(1)
7147(1)
7117(1)
6929(1)
7131(1)
6284(1)
6515(1)
7551(1)
6198(1)
3850(1)
7035(1)
5644(1)
6049(2)
4518(2)
3707(2)
3330(2)
3546(2)
1809(2)
2543(2)
3526(2)
2858(2)
2542(2)
2167(2)
2903(2)
3217(2)
7504(2)
7533(2)
7422(2)
9029(2)
8757(2)
9011(2)
8508(2)
8735(2)
8453(2)
8893 (2)
8556(2)
8786(2)
5438(2)
6072(2)
5799(2)
4880(2)
z
U(eq)
13121(1)
11243(1)
12806(1)
11612(1)
13830(1)
11383(1)
12827(1)
11601(1)
11264(1)
13784(1)
10750(1)
11965(1)
13558(1)
13644(1)
12602(1)
12516(1)
10386(1)
14196(1)
12264(1)
13300(1)
11944(1)
12222(2)
11392(2)
14138(2)
12368(1)
11794(1)
11977(2)
12765(2)
13342(1)
13174(1)
12245(1)
13202(1)
11803(1)
12194(2)
11085(2)
13901(2)
12290(1)
11649(2)
11761(2)
12495(2)
13158(2)
13053(2)
12552(1)
12561(1)
12618(1)
12669(1)
25(1)
26(1)
36(1)
33(1)
46(1)
40(1)
34(1)
34(1)
43(1)
48(1)
35(1)
33(1)
41(1)
35(1)
31(1)
33(1)
31(1)
34(1)
28(1)
34(1)
32(1)
43(1)
55(1)
58(1)
32(1)
37(1)
39(1)
46(1)
39(1)
37(1)
29(1)
38(1)
37(1)
52(1)
61(1)
63(1)
37(1)
43(1)
44(1)
50(1)
45(1)
43(1)
31(1)
31(1)
37(1)
41(1)
203
Table 3.5.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 7.a
atom
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(413)
C(414)
C(415)
C(416)
C(417)
C(418)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
C(509)
C(510)
C(511)
C(512)
C(513)
C(514)
C(515)
C(516)
C(517)
C(518)
C(601)
C(602)
C(603)
C(604)
C(605)
C(606)
x
-5463
-4661
-7499
-5358
-1192
-251
188
546
1257
812
486
-545
-1270
-1576
-1157
-425
-127
-3982
-4432
-4226
-3564
-3143
-1352
-839
266
821
481
-611
-1158
-1117
-1955
-2221
-1651
-826
-565
-2490
-2895
-3891
-4442
-3985
116
327
899
1287
1107
532
y
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(3)
(3)
(3)
(3)
4223
4526
6497
3234
6485
6725
6622
5636
5002
5093
6074
7720
8385
9289
9553
8906
8003
6286
6075
5177
4515
4774
7040
7441
7067
7480
8511
8917
8483
7124
7624
7308
6487
5979
6295
5457
5085
5325
5943
6288
10039
10546
11065
11119
10650
10087
z
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(3)
(3)
(3)
(3)
(3)
12668
12598
12618
12755
11326
11212
11949
12190
11568
10848
10605
10986
11447
11245
10574
10129
10323
10039
9481
9272
9620
10172
13798
14314
14048
14515
14473
14709
14258
15103
15559
16265
16511
16063
15365
14645
15256
15411
14968
14369
12662
13218
13030
12309
11753
11890
U(eq)
(1)
(1)
(2)
(2)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(2)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(1)
(2)
(2)
(2)
(2)
(1)
(2)
(2)
(2)
(2)
(2)
(1)
(2)
(1)
(1)
(1)
(3)
(2)
(3)
(3)
(2)
(3)
37 (1)
30 (1)
53 (1)
53 (1)
27 (1)
28 (1)
30 (1)
34 (1)
41 (1)
40 (1)
35 (1)
33 (1)
42 (1)
56 (1)
58 (1)
57 (1)
45 (1)
40 (1)
46 (1)
45 (1)
42 (1)
35 (1)
32 (1)
34 (1)
40 (1)
51 (1)
58 (1)
58 (1)
44 (1)
38 (1)
56 (1)
73 (1)
68 (1)
61 (1)
49 (1)
44 (1)
54 (1)
53 (1)
52 (1)
43 (1)
94 (1)
80 (1)
84 (1)
85 (1)
84 (1)
90 (1)
204
Table 3.5.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 7.a
atom
C(607)
C(608)
C(609)
C(610)
C(611)
C(612)
C(613)
C(614)
C(615)
x
-2637(3)
-3510(4)
-4156(3)
-3916(4)
-3024(4)
-2385(3)
-4730(11)
-4334(7)
-4302(10)
y
8175(3)
8859(3)
8913(3)
8301(3)
7594(3)
7535(3)
8994(10)
9498(7)
10320(10)
z
9755(2)
9825(2)
9320(3)
8749(3)
8680(3)
9195(3)
15185(9)
14670(5)
14304(8)
U(eq)
75(1)
86(1)
87(1)
90(1)
95(1)
81(1)
208(5)
133(3)
206(5)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
205
Table 3.6. Atomic coordinates (x 104) and equivalent
a
isotropic displacement parameters (A 2 x 103) for 12.
atom
Fe ()
Fe(2)
C1(1)
C1(2)
C1(3)
C1(4)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
N(401)
N(501)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(4)
C(5)
C(6)
C(7)
C(8)
C(119)
x
4521(1)
3725(1)
9398(3)
10020(2)
4173(3)
4353(4)
4739(2)
3976(3)
6857(2)
5297(2)
5150(2)
4765(2)
6442(2)
7803(2)
2250(3)
3179(2)
3967(3)
3706(3)
6118(2)
7209(2)
3596(3)
5909(2)
4257(3)
6241(3)
5389(3)
2888(4)
4445(3)
6138(3)
3917(3)
3781(3)
4742(3)
5305(3)
5568(3)
4617(3)
2246(5)
1667(12)
1037(17)
1308(18)
1927(17)
2529(11)
1517(7)
893(10)
975(13)
1588(11)
2230(7)
5265(3)
y
2895(1)
3963(1)
1821(2)
3436(2)
10020(3)
8644(2)
2369(2)
2909(2)
1788(2)
2977(2)
4096(2)
4739(2)
5585(2)
4217(2)
3752(3)
3303(2)
2774(2)
1812(2)
2356(2)
4941(2)
4534(2)
2592(2)
2316(3)
1702(2)
2357(2)
1248(3)
1520(3)
191(3)
1473(2)
1503(3)
1556(2)
855(2)
905(2)
853(3)
482(4)
321(11)
-439(18)
-941(12)
-1022(14)
-256(8)
620(7)
-41(9)
-837(12)
-996(8)
-258(6)
1658(3)
z
6088(1)
7469(1)
7584(3)
8244(2)
5607(2)
6399(3)
7033(2)
7826(2)
7845(2)
9409(2)
6309(2)
7258(2)
8687(2)
7091(2)
6985(2)
6309(2)
4853(2)
5503(2)
8666(2)
7918(2)
8454(2)
5925(2)
7504(2)
8186(2)
9063(2)
7120(3)
9756(2)
7950(2)
7673(2)
8443(2)
9029(2)
8858(2)
8134(2)
7545(2)
7200(4)
7495(9)
7543(13)
7141(12)
6627(13)
6630(8)
7701(6)
7799(8)
7407(10)
6957(8)
6927(5)
10429(2)
U(eq)
34(1)
33(1)
174(2)
143(1)
166(2)
177(2)
41(1)
43(1)
41(1)
39(1)
38(1)
38(1)
39(1)
42(1)
69(1)
42(1)
54(1)
55(1)
29(1)
30(1)
38(1)
47(1)
34(1)
31(1)
30(1)
48(1)
37(1)
41(1)
36(1)
35(1)
31(1)
33(1)
33(1)
38(1)
78(2)
62(4)
89(6)
74(5)
97(7)
56(4)
51(3)
76(4)
86(5)
68(4)
50(3)
40(1)
206
Table 3.6.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 12. a
atom
C(120)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(127)
C(128)
C(129)
C(130)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(219)
C(220)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
C(227)
C(228)
C(229)
C(230)
C(301)
C(302)
C(303)
C(304)
C(305)
x
5423
6128
6709
6582
5850
6995
7926
8701
8555
7646
6875
5146
7525
6767
4792
6800
8387
5578
5752
6737
7597
7508
6535
3765
3005
2041
1822
2544
3515
7712
8611
9440
9385
8493
7665
9404
9848
10770
11266
10849
9924
6678
7365
8207
8324
7645
y
(4)
(5)
(4)
(4)
(4)
(3)
(3)
(4)
(4)
(4)
(4)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(3)
(4)
(5)
(5)
(5)
(5)
(4)
(4)
(4)
(5)
(5)
(4)
(4)
(4)
(5)
(5)
(5)
(4)
(3)
(3)
(3)
(3)
(3)
2377 (3)
2501 (4)
1903 (4)
1195 (4)
1064 (3)
63 (2)
511 (3)
400 (3)
-154 (4)
-611 (4)
-507 (3)
4718 (3)
4847 (2)
5601 (2)
5732 (3)
7101 (3)
5587 (3)
5537 (2)
6231 (2)
6317 (2)
6343 (2)
5569 (3)
5471 (3)
5788 (3)
5151 (4)
5184 (5)
5859 (6)
6475 (5)
6446 (4)
7308 (3)
7672 (3)
7848 (4)
7678 (4)
7332 (4)
7143 (3)
5757 (3)
6544 (4)
6700 (6)
6061 (7)
5274 (6)
5128 (4)
3644 (2)
4330 (2)
4464 (3)
3884 (3)
3196 (2)
z
10896
11531
11725
11266
10626
8538
8642
9204
9657
9552
8989
6721
7278
8158
5888
8256
6477
6543
7170
7733
7370
6859
6272
5992
5671
5717
6119
6442
6366
8872
8782
9348
10025
10125
9553
6974
7260
7738
7939
7634
7170
8294
8392
8952
9423
9350
U(eq)
(3)
(3)
(3)
(3)
(3)
(2)
(3)
(4)
(3)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(2)
(3)
(5)
(4)
(3)
(3)
(3)
(3)
(4)
(4)
(3)
(3)
(3)
(3)
(4)
(4)
(5)
(4)
(2)
(2)
(2)
(2)
(2)
51 (1)
64 (2)
63 (2)
58 (1)
47 (1)
38 (1)
47 (1)
60 (1)
64 (2)
59 (1)
50 (1)
32 (1)
32 (1)
32 (1)
38 (1)
39 (1)
41 (1)
32 (1)
32 (1)
32 (1)
34 (1)
34 (1)
36 (1)
44 (1)
60 (1)
85 (2)
87 (2)
81 (2)
67 (2)
45 (1)
55 (1)
68 (2)
75 (2)
71 (2)
54 (1)
48 (1)
61 (1)
87 (2)
92 (3)
90 (3)
62 (2)
29 (1)
30 (1)
38 (1)
39 (1)
33 (1)
207
Table 3.6.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 12. a
atom
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
C(509)
C(510)
C(511)
C(512)
C(601)
C(602)
C(603)
C(605)
C(606)
C(607)
x
6826(3)
8968(4)
7783(3)
2342(4)
1452(4)
568(6)
-232(8)
-186(8)
663(7)
1499(5)
2847(4)
2755(5)
3459(5)
4188(5)
4221(5)
3598(4)
2995(4)
3019(4)
2460(5)
1867(5)
1834(6)
2404(5)
6375(3)
7246(4)
7652(4)
7186(4)
6314(4)
-363(17)
552(17)
884(26)
420(13)
4732(10)
9024(7)
y
3083(2)
5207(3)
2599(3)
3398(3)
3157(5)
3414(8)
3259(10)
2835(8)
2541(7)
2757(4)
4260(4)
4585(4)
5222(4)
5498(4)
5150(4)
2073(3)
1527(3)
1700(3)
1196(4)
520(4)
341(4)
842(4)
3014(3)
2795(4)
2154(4)
1731(4)
1950(3)
-778(14)
-952(14)
-597(22)
89(13)
9242(8)
2733(6)
z
8769(2)
9058(3)
9885(3)
6393(3)
5787(4)
5830(7)
5268(9)
4653(8)
4608(5)
5157(4)
8739(3)
9402(3)
9795(3)
9491(4)
8820(3)
4899(3)
4248(3)
3575(3)
2968(3)
3054(3)
3714(4)
4312(3)
5485(2)
5342(3)
5638(4)
6077(4)
6221(3)
4320(12)
4487(13)
5201(19)
5332(10)
5748(7)
7786(7)
U(eq)
29(1)
52(1)
45(1)
50(1)
79(2)
142(5)
186(8)
156(6)
121(4)
77(2)
60(1)
71(2)
59(1)
75(2)
63(2)
48(1)
48(1)
56(1)
66(2)
68(2)
85(2)
73(2)
66(2)
112(3)
155(5)
134(4)
91(3)
117(6)
120(6)
177(11)
191(7)
137(4)
116(3)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
208
Table 3.7. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 10 3 ) for 13. a
atom
Fe(1)
Fe(2)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
N(401)
N(501)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C (114)
C(115)
C(116)
C(117)
C(118)
C(119)
C(120)
C(121)
C(122)
C(123)
C(124)
C(125)
C(126)
C(127)
C(128)
x
6571(1)
6604(1)
5927(2)
5947(2)
6593(2)
6378(2)
7479(2)
7538(2)
8639(2)
8668(2)
6137(2)
6348(2)
6996(2)
5953(2)
6490(2)
8616(2)
6742(2)
6724(2)
5718(2)
6236(3)
6112(2)
4557(2)
5154(3)
5446(3)
5100(2)
4986(2)
5389(2)
5280(2)
5508(2)
5117(2)
3862(3)
3587(3)
2947(4)
2571(4)
2822(4)
3463(3)
5481(3)
6002(3)
6306(3)
6089(3)
5572(3)
5264(3)
4763(3)
4504(3)
3874(4)
3487(4)
y
6895(1)
8845(1)
7245(2)
8454(2)
6612(2)
9109(2)
7373(2)
8612(2)
9214(2)
6684(2)
9129(2)
7929(2)
6278(2)
6161(2)
7853(2)
7945(2)
9839(2)
5964(2)
7803(3)
7124(3)
8508(3)
7639(3)
9097(3)
6276(3)
7709(3)
8388(3)
8413(3)
7687(3)
7030(3)
6991(3)
7608(3)
6972(4)
6949(5)
7576(6)
8210(5)
8232(4)
9207(3)
9690(3)
9789(3)
9394(4)
8916(4)
8821(4)
6078(3)
6323(4)
6164(4)
5758(5)
z
727(1)
989(1)
1141(1)
1322(1)
2354(1)
2401(1)
1067(1)
1043(1)
2023(1)
2067(1)
295(1)
298(1)
214(1)
174(1)
2450(1)
2008(1)
1393(1)
1243(2)
1318(2)
2381(2)
2400(2)
1030(2)
2627(2)
2632(2)
1522 (2)
1826(2)
2368(2)
2621(2)
2364(2)
1821(2)
1077(2)
1201(2)
1252(3)
1149(4)
1001(4)
970(3)
3163(2)
3315(2)
3808(2)
4162(2)
4026(2)
3530(2)
2655(2)
3042(2)
3063(3)
2694(4)
U(eq)
25(1)
26(1)
35(1)
37(1)
35(1)
32(1)
25(1)
29(1)
32(1)
37(1)
46(1)
38(1)
40(1)
37(1)
24(1)
22(1)
29(1)
28(1)
27(1)
27(1)
26(1)
34(1)
34(1)
39(1)
26(1)
27(1)
26(1)
30(1)
28(1)
28(1)
39(1)
45(2)
70(2)
92(3)
106(4)
72(2)
34(1)
41(2)
48(2)
54(2)
62(2)
49(2)
43(2)
57(2)
76(2)
82(3)
209
Table 3.7.(cont'd) Atomic coordinates (x 104) and equivalent
a
2
isotropic displacement parameters (A x 103) for 13.
atom
C(129)
C(130)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(219)
C(220)
C(221)
C(222)
C(223)
C(224)
C(225)
C(226)
C(227)
C(228)
C(229)
C(230)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
x
3732(4)
4366(3)
7760(2)
8825(2)
8808(2)
8082(2)
9651(2)
9669(3)
8383(2)
8811(2)
9238(2)
9655(2)
9243(2)
8787(2)
8554(3)
8633(3)
9040(4)
9351(3)
9271(3)
8867(3)
10203(2)
10110(3)
10624(3)
11230(3)
11331(3)
10820(3)
10291(3)
10866(3)
11453(4)
11451(5)
10913(5)
10292(4)
7556(2)
8229(2)
8550(2)
8167(3)
7496(3)
7195(2)
9282(3)
7110(3)
6107(2)
5791(3)
5227(3)
4656(3)
4402(3)
4959(3)
y
5487(4)
5651(3)
7962(3)
7243(3)
8644(3)
7907(3)
9364(3)
6522(3)
7924(3)
8624(3)
8636(3)
7940(3)
7240(3)
7223(3)
7796(3)
7089(3)
6987(4)
7581(5)
8285(4)
8386(3)
9382(3)
9609(3)
9599(4)
9371(5)
9157(5)
9160(4)
6554(3)
6745(4)
6804(5)
6684(5)
6484(5)
6408(4)
7917(3)
7954(3)
7998(3)
8006(3)
7972(3)
7925(3)
8038(4)
7973(4)
8505(3)
8499(3)
9052(3)
8811(4)
8039(4)
7471(4)
z
2307(3)
2291(2)
997(2)
1882(2)
1854(2)
237(2)
1572(2)
1564(2)
813(2)
948(2)
1483(2)
1561(2)
1499(2)
972(2)
-92(2)
-275(2)
-598(2)
-747(2)
-577(2)
-252(2)
1315(2)
829(2)
596(3)
840(3)
1325(3)
1556(2)
1964(2)
1847(3)
2195(3)
2661(4)
2825(3)
2453(2)
2231(2)
2378(2)
2875(2)
3222(2)
3089(2)
2588(2)
3034(2)
3483(2)
74(2)
-483(2)
-597(2)
-379(3)
-557(3)
-447(2)
U(eq)
68(2)
52(2)
24(1)
26(1)
26(1)
32(1)
32(1)
32(1)
25(1)
27(1)
26(1)
29(1)
26(1)
27(1)
33(1)
44(2)
61(2)
65(2)
56(2)
43(2)
37(1)
50(2)
68(2)
76(2)
76(2)
53(2)
42(2)
60(2)
90(3)
100(3)
93(3)
81(3)
26(1)
25(1)
27(1)
29(1)
29(1)
24(1)
44(2)
43(2)
31(1)
36(1)
50(2)
61(2)
67(2)
54(2)
210
Table 3.7.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 13. a
atom
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(413)
C(414)
C(415)
C(416)
C(417)
C(418)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
C(509)
C(510)
C(511)
C(512)
C(513)
C(514)
C(515)
C(516)
C(517)
C(518)
C(601)
C(602)
C(603)
C(604)
C(605)
C(606)
C(607)
C(608)
C(609)
C(610)
C(611)
C(612)
C(613)
C(614)
C(615)
C(616)
x
5537(3)
6355(3)
6790(3)
7303(3)
7389(4)
6953(6)
6434(5)
7340(3)
7464(3)
6965(3)
6342(3)
6254(3)
6455(3)
6416(3)
5793(3)
5778(3)
6360(3)
6984(3)
7008(3)
6448(3)
7029(4)
7079(5)
6549(5)
5963(4)
5917(4)
6212(3)
6257(3)
6855(4)
7377(3)
7301(3)
10405(4)
11049(5)
11474(4)
11240(6)
10578(6)
10172(4)
8259(6)
8407(7)
8497(8)
8422(7)
8234(6)
8168(7)
6854(8)
6398(9)
6677(8)
7399(8)
y
7705(3)
8724(3)
8222(4)
8438(5)
9143(5)
9655(5)
9444(4)
10124(3)
10738(3)
11094(3)
10814(3)
10187(3)
5964(3)
5338(3)
4880(3)
4406(3)
3901(4)
4356(4)
4813(3)
5740(3)
6017(5)
6376(6)
6479(4)
6227(6)
5848(5)
5555(3)
5011(3)
4866(3)
5266(3)
5809(3)
6630(6)
6739(6)
6153(8)
5468(7)
5383(6)
5960(6)
5431(9)
5298(7)
5927(9)
6677(8)
6817(9)
6149(13)
6964(9)
6383(12)
5737(10)
5392(9)
z
-653(2)
-720(2)
-814(2)
-1016 (2)
-1125(3)
-1047(4)
-845(3)
1553(2)
1849(2)
1989(2)
1824(2)
1530(2)
39(2)
-353(2)
-405(2)
42(2)
186(3)
267(2)
-187(2)
-835(2)
-901(3)
-1335(3)
-1701(3)
-1646(3)
-1213(3)
1295(2)
1649(2)
1964(2)
1903(2)
1547(2)
356(3)
401(3)
520(4)
614(4)
562(3)
437(3)
-2594(6)
-2101(5)
-1822(5)
-2014(5)
-2483(6)
-2780(6)
4581(5)
4401(6)
4588(6)
4712(5)
U(eq)
43(2)
40(2)
53(2)
63(2)
83(3)
135(5)
106(3)
38(1)
51(2)
44(2)
42(2)
33(1)
32(1)
34(1)
43(2)
54(2)
59(2)
54(2)
45(2)
41(2)
89(3)
105(3)
81(2)
89(3)
75(2)
36(1)
47(2)
49(2)
43(2)
33(1)
84(3)
92(3)
103(4)
114(4)
98(3)
82(3)
130(4)
142(5)
163(5)
143(4)
151(6)
176(7)
177(5)
212(7)
185(6)
174(5)
211
Table 3.7.(cont'd) Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 10
atom
C(617)
C(618)
x
7784(7)
7521(8)
y
5981(9)
6674(10)
3
) for 13.
z
4666(5)
4648(6)
a
U(eq)
160(5)
187(6)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
212
Table 3.8. Atomic coordinates (x 104) and equivalent
isotropic displacement parameters (A2 x 103) for 16. a
atom
Fe(1)
Fe(2)
0(101)
0(102)
0(103)
0(104)
0(201)
0(202)
0(203)
0(204)
0(401)
0(402)
0(501)
0(502)
N(101)
N(201)
N(401)
N(402)
N(501)
N(502)
C(101)
C(102)
C(103)
C(104)
C(105)
C(106)
C(107)
C(108)
C(109)
C(110)
C(111)
C(112)
C(113)
C(114)
C(115)
C(116)
C(117)
C(118)
C(201)
C(202)
C(203)
C(204)
C(205)
C(206)
C(207)
C(208)
x
5968(1)
5554(1)
4980(2)
4774(1)
2126(2)
2648(1)
5488(1)
5741(1)
4107(1)
2963(1)
7068(1)
7248(1)
7068(2)
6523(2)
2351(2)
3514(2)
5160(2)
4120(2)
4625(2)
3101(2)
4696(2)
2264(2)
2550(2)
5291(2)
2193(2)
1701(2)
4293(2)
3759(2)
2601(2)
1928(2)
2342(2)
3521(2)
6178(2)
7106(3)
495(2)
-31(3)
1072(2)
742(4)
5728(2)
3527(2)
4158(2)
7243(2)
4992(2)
3762(2)
6045(2)
5981(2)
y
7038(1)
6659(1)
5883(1)
5217(1)
5572(1)
4324(1)
8144(1)
8090(1)
8529(1)
8551(1)
6638(2)
7274(1)
7699(1)
6054(1)
4925(1)
8569(1)
6491(2)
5955(2)
6889(2)
7033(2)
5134(2)
4879(2)
4186(2)
3888(2)
2349(2)
3775(2)
4095(2)
3292(2)
3224(2)
3048(2)
3927(2)
4061(2)
3892(3)
3672(3)
3539(2)
3554(4)
2137(2)
1238(3)
8554(2)
9019(2)
9008(2)
10100(2)
10615(2)
10618(2)
9705(2)
10104(2)
z
8216(1)
6590(1)
7572(1)
6638(1)
7614(1)
5805(1)
7810(1)
6871(1)
5896(1)
7661(1)
6755(1)
7710(1)
9001(1)
8835(1)
6706(1)
6775(1)
5677(1)
4806(1)
8666(1)
8872(1)
7171(1)
7311(1)
6306(1)
7659(1)
6003(1)
8044(1)
7336(1)
6784(1)
6529(1)
7020(1)
7534(1)
7786(1)
7305(1)
7661(2)
7876(1)
8423(2)
5675(2)
5203(2)
7377(1)
7356(1)
6376(1)
7768(1)
6031(1)
8028(1)
7464(1)
6872(1)
U(eq)
21(1)
23(1)
36(1)
27(1)
31(1)
27(1)
27(1)
27(1)
29(1)
29(1)
35(1)
32(1)
33(1)
33(1)
22(1)
21(1)
27(1)
31(1)
27(1)
37(1)
22(1)
24(1)
23(1)
30(1)
32(1)
33(1)
23(1)
24(1)
24(1)
27(1)
25(1)
26(1)
42(1)
58(1)
40(1)
74(1)
45(1)
109(2)
23(1)
23(1)
22(1)
36(1)
30(1)
29(1)
25(1)
27(1)
213
Table 3.8.(con't) Atomic coordinates (x 104) and equivalent
a
isotropic displacement parameters (A2 x 103) for 16.
atom
C(209)
C(210)
C(211)
C(212)
C(213)
C(214)
C(215)
C(216)
C(217)
C(218)
C(301)
C(302)
C(303)
C(304)
C(305)
C(306)
C(307)
C(308)
C(401)
C(402)
C(403)
C(404)
C(405)
C(406)
C(407)
C(408)
C(409)
C(410)
C(411)
C(412)
C(413)
C(414)
C(415)
C(416)
C(417)
C(418)
C(419)
C(420)
C(501)
C(502)
C(503)
C(504)
C(505)
C(506)
C(507)
C(508)
x
4862(2)
4368(2)
4250(2)
5369(2)
7551(3)
8652(3)
2666(2)
2230(3)
3984(2)
4206(3)
2935(2)
2746(2)
1821(2)
1112(2)
1275(2)
2195(2)
1572(2)
445(2)
7622(2)
8829(2)
9235(2)
9135(3)
9705(3)
9323(2)
9435(2)
8970(2)
8376(3)
8491(3)
9224(3)
9832(3)
9709(2)
5777(2)
5140(2)
4172(2)
3144(3)
2814(3)
2476(3)
2035(3)
7003(2)
7443(2)
7738(2)
8689(3)
9654(3)
9380(3)
8429(2)
6525(2)
y
10090(2)
10624(2)
10098(2)
10109(2)
9806(3)
10464(3)
10715(2)
11130(3)
10586(2)
11263(2)
6736(2)
7590(2)
7535(2)
6585(2)
5712(2)
5808(2)
8460(2)
4712(2)
7122(2)
7582(2)
6888(2)
5887(3)
6014(3)
6699(2)
7705(2)
8584(2)
8641(3)
9539(3)
10408(3)
10376(3)
9476(2)
6370(2)
6035(2)
6232(2)
5603(2)
6441(2)
7124(2)
7866(3)
6871(2)
6878(2)
5914(2)
5855(3)
6769(3)
7731(3)
7792(3)
6955(2)
z
6575(1)
7025(1)
7562(1)
7866(1)
8347(2)
8677(2)
7830(1)
8352(1)
5630(1)
5170(1)
6715(1)
6549(1)
6169(1)
5944(1)
6097(1)
6492(1)
6017(1)
5847(1)
7255(1)
7265(1)
6847(1)
7050(2)
7678(2)
8099(2)
7898(1)
7038(1)
6509(1)
6302(2)
6610(2)
7129(2)
7345(2)
5247(1)
4714(1)
5391(1)
4361(1)
4117(1)
4557(1)
4264(2)
9176(1)
9829(1)
9892(1)
9593(2)
9825(2)
9762(2)
10064(1)
10161(1)
U(eq)
24(1)
26(1)
24(1)
27(1)
50(1)
69(1)
35(1)
45(1)
40(1)
47(1)
21(1)
22(1)
24(1)
26(1)
24(1)
20(1)
39(1)
33(1)
28(1)
29(1)
43(1)
54(1)
57(1)
43(1)
33(1)
34(1)
48(1)
61(1)
65(1)
64(1)
48(1)
30(1)
33(1)
29(1)
44(1)
42(1)
42(1)
59(1)
28(1)
33(1)
41(1)
54(1)
62(1)
55(1)
44(1)
32(1)
214
Table 3.8.(con't) Atomic coordinates (x 104) and equivalent
a
2
isotropic displacement parameters (A x 103) for 16.
atom
C(509)
C(510)
C(511)
C(512)
C(513)
C(514)
C(515)
C(516)
C(517)
C(518)
C(51D)
C(519)
C(520)
x
6180(2)
5350(3)
4830(3)
5152(2)
5997(2)
4282(2)
3340(2)
3898(2)
2165(3)
2352(5)
2248(9)
3233(6)
3378(6)
y
7798(2)
7884(3)
7124(3)
6272(3)
6197(2)
6262(2)
6347(2)
7339(2)
7395(4)
8172(4)
8266(9)
8992(5)
9630(4)
z
10171(1)
10456(1)
10734(1)
10728(1)
10448(1)
9061(1)
9191(1)
8567(1)
8870(2)
9516(3)
9105(6)
9631(2)
10219(3)
U(eq)
37(1)
44(1)
46(1)
43(1)
37(1)
30(1)
37(1)
34(1)
65(1)
55(2)
52(4)
120(2)
120(2)
aNumbers in parentheses are estimated standard deviations of
the last significant figure. bU(eq) is defined as one third
of the trace of the orthogonalized Uij tensor.
215
Table 3.9. Effect of ligand steric and electronic properties and solvent on stable
peroxo adduct formation.
midnight blue solution: kmax = 580 (1200-1300)
or decomposition
-80 OC
THF, toluene, or CH2CI2
Complex
L
N
R
10-12
BXDK
py
i-Pr, Ph or CH 2 C(CH3)3
Compatible Solvents For
Stable Peroxo Formation
None
tert-Bu
THF or PhCH 3
4:L
Ph
THF, PhCH 3 , or CH2C12
THF, PhCH 3 , or CH 2C12
XDK
Ph
THF, PhCH 3 , or CH 2 C12
THF, PhCH 3 , or CH 2 C12
THF, PhCH 3, or CH 2C12
3-F-py
Me-Im
16
PXDK
16
PXDK
Bu-Im
Y-Ph
THF
Ph
THF or PhCH3
THF or PhCH 3
216
Table 3.10. Manometric studies of the dioxygen uptake for 13, 16, and [Fe(Tp 3 ,5iPr2)(0 2 CH 2 Ph)] vs. equimolar Vaska's complex.a
Compound
Solvent
02 Uptake,
Peroxo Formation
02 Uptake, Peroxo
Decay (equiv)
(equiv)
IrCl(CO)(PPh 3 )2
CH 2Cl 2
1.0
-
(13)
CH 2C12
1.0 + 0.1
0.7 + 0.1
[Fe(Tp 3 ,5-iPr 2 )(0 2 CH 2 Ph)]
THF
0.55 ± 0.1
0.3 ± 0.1
[Fe(Tp 3 ,5-iPr 2 )(O2CH2Ph)]
Et 20
THF
0.45 ± 0.1
0.9 ± 0.1
0
1.0 + 0.1
16
16
Et 20
1.0 + 0.1
0
aAll 02 uptake values are in equivalents based on the amount of 02 uptake by
equimolar Vaska's complex under identical conditions. T = -77 'C for the formation
and 22 oC for the decay. In each case following decay, the system was brought back to
equilibrium at -77 'C for the final pressure reading.
217
Table 3.11. A summary of resonance Raman data obtained for the peroxo adducts.
Compound
solvent
v(Fe- 160) (180)
[Fe 2 (0 2 )(BXDK)(p-O 2 Ct-Bu)-
toluene
Not Observeda
864
toluene
Not Observed
864
toluene
Not Observed
864
toluene
Not Observed
864
(13-02)
CH 2 C12
484 (484)
861 (811)
[Fe 2 (0 2)(BXDK)(g-0 2CAr)-
toluene
Not Observed
864
toluene
Not Observed
864(818)
v( 160-
160)
(1802)
(O2Ct-Bu)(py)2] (6-02)
[Fe 2 (0 2 )(XDK)(9-0 2 CPhCy)(02CPhCy)(py)21 (7-02)
[Fe 2 (0 2 )(XDK)(9-O 2 CAr)(O2CAr)(py)21 (8.02)
[Fe 2 (0 2 )(BXDK)(gj-O
2 CPhCy)-
(O2CPhCy)(py)2] (13-02)
(O2CAr)(py)2] (14-02)
[Fe 2 (0 2 )(PXDK)(ji-O 2 CPhCy)(O2 CPhCy)(Bu-Im) 2 ] (16-02)
aFe-O stretches were not observed for the toluene samples. These features were
likely obscured by the large solvent background in this region, overwhelming even
with solvent subtraction.
218
Table 3.12. M6ssbauer parameters for [Fe 2 (BXDK)(pt-02CPhCy)(0 2 CPhCy)(py) 2 ] (13),
[Fe 2 (XDK)(g-O 2 CPhCy)(O 2CPhCy)(Me-Im)2] (15), and [Fe 2 (0 2 )(BXDK)(O2 CPhCy)2(py)2] (13.02).
Complex
8 (mm/s)
AEQ (mm/s)
F1/2 (mm/s)
13 (solid)
1.27
3.03
2.54
0.39
0.37
or
1.07
13 (THF soln.)
15 (THF soln)
or
1.29
1.05
or
2.98
2.58
0.38
1.23
3.10
0.47
1.22
2.61
0.50
or
or
or
1.34
2.87
0.50
1.10
1.24
2.85
0.47
0.43
1.26
Oxyhemerythrin
MMOHperoxo
aThis work.
0.44
1.36
1.14
2.94
or
0.44
2.98
0.43
0.62
1.22
0.42
0.48
or
0.64
0.86
or
1.18
0.42
0.46
0.51
0.52
0.66
0.89
1.96
0.95
1.51
0.42
0.30
0.36
0.27
or
13.02
3.19
2.73
or
0.38
or
0.41
ref
219
Table 3.13. Summary of kinetic data for the reaction of the diferrous complexes with
oxygen at -77 'C, and a correlation with selected solid state metrical parameters.
Parameter
6
7
13
14
k (M-ls- 1)
0.0398 ± 0.0009
0.045 ± 0.003
0.16 ± 0.01
0.115 + 0.005
Fe2-0402
2.340(2)
2.454(2)
2.489(4)
Fe2-0401
2.062(2)
2.050(2)
2.017(4)
Fel-0402
2.172(2)
2.217(2)
2.194(4)
Fel-0402-Fe2
102.13(9)
100.47(6)
98.96(13)
Not
Fel-0402-C401
170.6(2)
171.5(2)
168.0(3)
Availablea
Fe2-0401-C401
97.5(2)
100.15(13)
101.5(3)
Fe2-0402-C401
84.5(2)
81.84(12)
80.3(3)
tb
73
71
66
aAn X-ray structure was acquired for 14, but it was of insufficient quality for
an accurate determination of bond distances and angles. bSee Figure 3.11 for a
complete definition of
t.
220
/N
N-
XDK
N---
rN-Fe
S
XD4
XDK
PhCy
,
o
O
\- YOU/
BXDK
t-Bu
O
N
Fe
..
XDK
6
o
7
XDK
i-Pr
-"
/
FFe
o
i-Pr
0
\
XDKO
XDK
CH2 t-Bu
O4
oFe
F.D
1Fe
y(
N
N
8
CH2 t-Bu
O0
Ar
O:
Fe.,
,PhCy
-O
F
Ar
\
'
e,
BXDK
t-Bu
O
BXDK
F
BXDK
9
10
BXDK
11
BXDK
14
PhCy
O -:40PhCy
Fe
.
F
BXDK
BXDK
12
XDK
Scheme 3.1.
15
o
13
PXDK
16
221
Rate-Determining Carboxylate
Shift Concominant With
02 Attack
R
Fel
N/
\o o/\
N
or
O
N
0
NN
-i: el!!,,
0
Fell-"0
1e- transfer?
R
0I3O
Fe
d
Fe
O
0
N
b
Superoxo or Peroxo
for a orb?
Scheme 3.2.
Fast Ligand
Rearrangement
a
Slow
0
N
R
I
NF ! 1."0 OO/ Fe ll\.
J.e/
,.,
o
222
Tyr 1~2
OH
Glu 115
Glu 204
His 241
His 118
A.
G
lu
209
Glu 114
Fe...Fe = 3.3-3.4 A
His 246
Glu 144
Glu 243
Glu 114 0 ----H20
H
O
..-------.0
O
'O/
Gu,-209
'
Fe...Fe = 3.1 A
His 147
N
0N
OH
C.
Glu 144
Glu
HN
His 246
Figure 3.1. Chemdraw representations of the active site structures of: (A) reduced R2,
(B) reduced MMOH (Hred), and (C) oxidized MMOH (Hox).
223
I Ribonucleotide Reductase I
0
R2act(Tyr1220-) + H20 + F/
2Fell + e- + 02 + R2apo(Tyrl220H) H4
0__e
H
O
0'
__
Fell' \ wo F"'eeV
k= 60-80 s-1
I
k = 0.7-1 s - 1
0
/ \
H'OF"
FeV
/..
\eFC_..Fel
Putative Peroxo
Intermediate X
UVNis: Arnax = 360-365 nm
M6ssbauer: 8 = 0.56 mm/s, AEG = -0.9 mm/s
8 = 0.26 mm/s, AEo = -0.6 mm/s
EPR/ENDOR: S = 1/2 Ground State
Possible Q-Like Intermediate:
Thus Far Undetected
M6sabauer: 8 = 0.66 mm/s, AEo = 1.51 mm/s
UV-Via: Ax = 500-750 nm
Fe11
(Fe (S = 5/2) - Fe(S = 2))
EXAFS: Fe...Fe = 2.5 A, Fe-O = 1.8 A
Soluble Methane MonooxygenaseI
OH
CH 4
Felil Fell
CH 4
CH 4
2e-
Fell
02
Fell
k - 25 s
Fe
-1
\
k - 0.5 s -1
CH4
OH
e
.
k - 0.05 s-1
er
CH3OH
2H+
H2 0
**r
Intermediate 0
UVNis: kmax = 350 (E - 6000 M-lcm -1) and
420 (e - 7000 M-'cm- 1)
M6ssbauer: 8 = 0.21 mm/s, AEa = 0.68 mm/s
8 = 0.14 mm/s, AEo = 0.55 mm/s
EPR: S = 0 Ground State
F
Fev
O\ CH 4
FetV
or a related
structure
Fe"'
Hperoxo Intermediate
M6ssbauer: 8 = 0.66 mm/s, AEQ = 1.51 mm/s
UV-Vis: kmax = 725 nm (E- 1500 M-1cm- 1)
EPR: S = 0 Ground State
(Fe (S = 5/2) - Fe(S = 5/2))
y-irradiation
0
Fe ,,,.Fel
Intermediate Qx
-----
Mfssbauer: 8 = 0.48 mm/s, AEo = -0.9 mm/s
8 = 0.14 mm/s, AEo = -0.6 mm/s
(Fe (S = 2) - Fe(S = 2))
EXAFS: Fe...Fe = 2.45 A,2 Fe-O at 1.77 A
Figure 3.2. A summary of mechanisms elucidated for tyrosyl radical generation in
the R2 subunit of ribonucleotide reductase, and for the catalytic oxidation of
methane in sMMO.
224
Figure 3.3. ORTEP diagram of [Fe2(BXDK)(.-O2 Ctert-Bu)(O2 Ctert-Bu)(py)2 ] (6) with
50% thermal ellipsoids.
F
o
OFe
Figure 3.4. Space-filling representations of [Fe 2 (PXDK)(O 2Ct-Bu)(-02Ct-Bu)(Me-m)2] from ref. 25 and
Fe vector.
[Fe2 (BXDK)(O 2Ct-Bu)(-O02 Ct-Bu)(py)2] (6), looking down the Fe ...
L--
=~
226
0(502)
0(401)
F
N(401) ,
Figure 3.5. ORTEP diagram of [Fe2(XDK)(pt-O 2 CPhCy)(O 2 CPhCy)(py) 2 ] (7) with 50%
thermal ellipsoids.
227
Figure 3.6. Space-filling representation of [Fe2(XDK)(g-O2CPhCy)(O 2 CPhCy)(py) 2] (7).
228
Ci402)
C(5021
0(502)
C(401)
0(402)
C(501)
0(501)
Fe(1)
0(101)
C(107)
0(202)
N401)
C(201)
C(207)
Figure 3.7. ORTEP diagram of [Fe2(XDK)(I-O2CPhCy)(O2CPhCy)(py) 2 ] (7) with 50%
thermal ellipsoids, highlighting the iron coordination spheres. All other ORTEP
and space-filling diagrams in Figures 3.3 and 3.5-3.10 are presented with identical
orientations and numbering schemes.
229
Figure 3.8. ORTEP diagram of [Fe2(BXDK)(-O2CPh)(O2CPh)(py) 2] (12) with 50%
thermal ellipsoids. Atoms represented as open circles were refined isotropically.
230
Figure 3.9. ORTEP diagram of [Fe2(BXDK)(I-O2CPhCy)(O 2 CPhCy)(py) 2 ] (13) with 50%
thermal ellipsoids.
231
Figure 3.10. ORTEP diagram of [Fe2(PXDK)(p-O 2PhCy)(O 2PhCy)(Bu-Im) 2] (16) with
50% thermal ellipsoids. The PXDK carbon atom represented as an open circle was
refined isotropically.
232
R
O
a
D
"
Fe'
Fe
r = a - p = tilt
PhCy
2
'O
Increasing Steric Repulsions
More Basic N-Donor
BXDK
b
Bu
12
PXDK
Bu
16
12
6
7
13
16
XDK Deriv.
BXDK
BXDK
XDK
BXDK
PXDK
Ancil. Carbox.
Ph
tert-Bu
PhCy
PhCy
PhCy
N-Donor
py
py
py
py
Bu-Im
B = Fe2-0402
2.317(3)
2.340(2)
2.454(2)
2.489(4)
3.055(2)
D = Fe2-0401
2.047(4)
2.062(2)
2.050(2)
2.017(4)
2.006(4)
A = Fel-0402
2.184(3)
2.172(2)
2.217(2)
2.194(4)
2.154(2)
e = Fel-0402-Fe2
102.55(12)
102.13(9)
100.47(6)
98.96(13)
87.72(6)
a = Fel-0402-C401
168.9(3)
170.6(2)
171.5(2)
168.0(3)
152.6(2)
y = Fe2-0401-C401
96.3(3)
97.5(2)
100.15(13)
101.5(3)
116.6(2)
p = Fe2-0402-C401
84.6(3)
84.5(2)
81.84(12)
80.3(3)
67.46(15)
73
73
71
66
36
z=a -
Figure 3.11. A schematic illustration of the effect of ligand substituent steric
repulsion on the orientation of the bridging ancillary carboxylate, including the
relevant metrical parameters which account for this effect.
233
1400
1200
'1000
EE 800
W 600
400
2001
300
I
400
I
500
I
600
I
700
I
800
X(nm)
2000
7000
6000
1500
5000
E4000
13 + 0
C 1000 -
0
3000
500 -
2000
13
1000
01
300
400
500
600
X (nm)
700
0
300
800
I
400
I
500
I
600
I
700
800
700
800
X (nm)
2000
7000
6000
1500
5000
E
E
4000
13000
2000
500
1000
0 L
300
400
500
600
X (nm)
700
800
0
300
400
500
600
X (nm)
Figure 3.12. Representative UV-Vis spectra for the reaction of diferrous complexes 615 with 02 at -80 oC: (A) [Fe2(BXDK)(g-O 2Ct-Bu)(02Ct-Bu)(py) 2 ] (6), [Fe 2 (BXDK)(RO2CPhCy)(O 2 CPhCy)(py) 2 ] (13), and [Fe2(PXDK)(Q-O 2 CPhCy)(O 2 CPhCy)(Bu-Im) 2 ] (16).
234
5.5 105
5 10 s
0
8o 4.5410
10s5
3.5 105
3 10 s
780
800 820 840 860
Raman Shift (cm-)
880
780
800 820 840 860
Raman Shift (cm')
880
840 860
820
Raman Shift (cm')
880
1.6 1
1.4 11
0)
c 1.2 11
.0
1 1
8 1
1.2 105
1.12 105
a1.04 105
o
4
9.6 10
8.8 104
8 104
780
800
Figure 3.13. Resonance Raman spectra obtained with 647 nm excitation on fluid
toluene solutions (-80 'C) of: (A) [Fe 2(160 2)(PXDK)(O 2CPhCy) 2(Bu-Im) 2] (16.1602), (B)
[Fe 2(180 2)(PXDK)(O 2 CPhCy) 2(Bu-Im) 2 ] (16.1802), and toluene. Peaks marked with an
asterisk in A and B are due to toluene.
235
A.
0.05
864 cm "
0.04 " 0.03
.0
o
" 0.02
0.01
800 810 820 830 840 850860 870 880
Raman Shift (cm-1 )
0.05
0.04 -
818 cm'1
0.03
0.02
0.01
I
I
I
III
I
OL
8C0 810 820 830 840 850860 870 880
Raman Shift (cm-')
3
2.8
S2.6
- 2.4
o
- 2.2
2
800 810820 830 840 850 860 870 880
Raman Shift (cm')
Figure 3.14. Solvent subtracted resonance Raman spectra for: (A) [Fe 2 (16 0 2 )(PXDK)(0 2 CPhCy) 2 (Bu-Im)2] (16.1602, normalized to the 788 cm -1 toluene peak), (B)
[Fe 2 (18 0 2 )(PXDK)(O 2 CPhCy) 2 (Bu-Im)2] (16.1802, normalized as above), and (C)
16.1802 minus 16.1602 (scaled prior to subtraction).
236
3.50 105
3.40 105
3.30 105
Co
C
3.20 105 .0
3.10 105
3.00 105
2.90 105 800
820
840
860
Raman Shift (cm1 )
880
900
820
840
860
Raman Shift (cm-1 )
880
900
0.000200
0.000180
O 0.000160
CIS
0
0.000140
0.000120
0.000100
800
Figure 3.15. (A) Resonance Raman spectrum obtained with 647 nm excitation on a
fluid toluene solution (-80 oC) of [Fe2(02)(PXDK)(02CPhCy) 2 (Bu-Im)2] (16-02),
prepared from 16 and a 1:2:1 mixture of 1602, 160180, and 1802. (B) Toluene solvent
background subtracted from the spectrum in A (normalized to the 788 cm-1 toluene
peak).
237
-3
-2
-1
0
1
2
1
S(mm s )
3
4
5
-3
-2
-1
0
1
2
1
8 (mm s )
3
4
5
Figure 3.16. M6ssbauer spectra (experimental data (o), calculated fit (-)) of
[Fe2(BXDK)(-O2CPhCy)(O2CPhCy)(py)2] (13), recorded in THF solution (Top) and in
the solid state (Bottom), at 77 K.
238
-3
-2
-1
0
1
6 (mm
2
3
4
5
s "1)
Figure 3.17. M6ssbauer spectrum (experimental data (.), calculated fit (-)) of
[Fe2(XDK)(g-O 2 CPhCy)(O 2 CPhCy)(Me-Im) 2 ] (15), recorded in THF solution at 77 K.
239
~55:.::
:'
v..
f
r
t
~~
-v~
~j4 L;Lt
.~
i...
;'*Cz'
r
:.::"
c
C
I
I
I
-4
-3
-2
-1
0
1
1)
6 (mm s
2
3
-4
-3
-2
-1
2
3
0
1
"
1
6 (mm s )
4
Figure 3.18. M6ssbauer spectrum of 13-02 recorded in THF solution at 77 K: (Top)
experimental data, and (Bottom) experimental data (*) with the diferrous
component removed by subtraction and a calculated fit (-) to these data.
240
0.640.560.480.40.320.24k =6.398 x 10 + 8 x 107 s'
0.16-
W
0.08ni.#
0
II
I
I
I
I
I
I
500 1000 1500 2000 2500 3000 3500 4000
Time (sec)
0.0007
y = 2.4623e -05 + 0.039796x R= 0.99922
0.0006-
0.0005
Ca,
d
,i.L
0.00040.00030.0002-
0.0001
I
I
0.002 0.004 0.006 0.008 0.01
[O21 (M)
-7.2
I
I
I
0.012 0.014 0.016
y = -3.6689 +(
-7.4-7.6-7.8-8
-6
-5.5
-5
-4.5
-4
In([0 2])
Figure 3.19. Kinetic data for the reaction of [Fe2(BXDK)(p-O2Ct-Bu)(O 2 Ct-Bu)(py) 2 1 (6)
with 02 in THF at -77 °C: (Top) plot of A 600 vs. time with [6]0 = 0.73 mM and [021 =
15.4 mM and a fit to a first order exponential buildup, (Middle) plot of kv vs. [021,
and (Bottom) plot of ln(ky) vs. ln([02]).
241
0.5
*
0.40.3-
0.2k =7.027 x 104 ± 5 X 107 s
0.1-
1
N'
0- 1
0
500
1000
1500
2000
2500
3000
3500
4000
-
Time (sec)
0.00080.00070.0006
0.0005.
0.00040.0003-
0.00020.0001 -0.002 0.004
0.006 0.008
0.01
0.012 0.014
0.016
[0 2] (M)
-7
-7.5-
-8.5
-5
In ([0
])
Figure 3.20. Kinetic data for the reaction of [Fe2(XDK)(-O2CPhCy)(hCy)(Cy)(py) 2 1 (7)
with 02 in THF at -77 'C: (Top) plot of A600 vs. time with [7]0 = 0.56 mM and [021 =
15.4 mM and a fit to a first order exponential buildup, (Middle) plot of kv vs. [021,
and (Bottom) plot of ln(kv) vs. ln([O21).
242
0.25
0.2o 0.150.1k = 2.576 x 10-3
2 x 10 s 1
0.05 -
0
0.003
----
200
400
600
Time (sec)
800
1000
y = 0.00015752 + 0.15853x R= 0.99425
0.0025,
0.002-
~0.00150.0010.0005
0.002 0.004 0.006 0.008
0.01
0.012 0.014 0.016
[02 (M)
-5.5
y = -2.1023 + 0.92029x R= 0.99698
-62-'-6.5-
-7-
-7.5
-6
-5.5
-5
In ([021)
-4.5
-4
Figure 3.21. Kinetic data for the reaction of [Fe2(BXDK)(-O2CPhCy)(O2CPhCy)(py) 2 ]
(13) with 02 in THF at -77 'C: (Top) plot of A 600 vs. time with [13]0 = 0.41 mM and
[021 = 15.4 mM and a fit to a first order exponential buildup, (Middle) plot of kg vs.
[02], and (Bottom) plot of ln(kV) vs. ln([O2]).
243
0.35
0.3
0.25
<
o
o
0.2
0.15
0.1
0.05
0
0
0.002
500
-
1000
1500
2000
Time (sec)
2500
3000
y = 5.9611e-05 + 0.11545x R= 0.99718
0.0015-
S0.001
0.0005
0.002
I
I
I
1
0.002 0.004 0.006 0.008 0.01
[021 (M)
I
I
I
0.012 0.014 0.016
-6.5
-6
-5.5
-5
In ([0 ])
-4.5
-4
Figure 3.22. Kinetic data for the reaction of [Fe2(BXDK)(-O22CAr)(02CAr)(py) 2] (14)
with 02 in THF at -77 OC: (Top) plot of A 600 vs. time with [14]0 = 0.39 mM and [021 =
15.4 mM and a fit to a first order exponential buildup, (Middle) plot of kv vs. [02],
and (Bottom) plot of ln(kv) vs. ln([021).
Chapter IV
The Reactivity of Well Defined Diiron(III) Peroxo Complexes Towards Substrates:
Addition to Electrophiles and Hydrocarbon Oxidation
245
Introduction
The selective and efficient catalytic oxidation of hydrocarbon substrates under
mild conditions continues to be a formidable goal for the synthetic chemist. 1,2 In
Nature, obligate methanotrophic bacteria carry out one of the most challenging
types of these reactions, the conversion of methane to methanol under ambient
conditions (eq 1), utilizing a soluble3 -5 or particulate 6,7 methane monooxygenase
CH4 + 02 + NADH + H+ -
CH 3OH + H20
+ NAD +
(1)
(sMMO or pMMO). The soluble form houses a diiron center in its hydroxylase
component (MMOH), the site of methane oxidation. This protein is a member of a
class of non-heme diiron enzymes which carry out a variety of selective
hydrocarbon oxidative processes. 35,s A closely related enzyme is ribonucleotide
reductase, which uses 02 at a diiron center in its R2 subunit (RNR-R2) to generate a
tyrosyl radical which in turn assists in the catalytic reduction of ribonuleotides. We
seek to prepare functional synthetic models of these systems, with the goals of
aiding in the elucidation of the biological 02-activation mechanisms, and to develop
practical hydrocarbon oxidation catalysts.
The current state of knowledge regarding these systems, including their
structural, spectroscopic, and mechanistic ties, was described in detail in Chapter 3;
therefore, only a brief review will be provided here. Metal-oxygen intermediates
have been characterized for sMMO 4,8,9 and RNR-R2 10 -12 by coupling stopped-flow
and rapid freeze quench methods to a variety of spectroscopies. Both proteins react
with 02 in their diferrous forms to afford a diiron(III) peroxo complex as the first
detected intermediate. For sMMO, this species converts to a diiron(IV) species, Q,
which is believed to be the active substrate oxidant. In RNR-R2, the peroxo converts
to a diiron(III)(IV) complex, X, possibly through a diiron(IV) intermediate like
246
sMMO-Q. Intermediate X reacts with an adjacent tryrosine, formally by hydrogen
atom abstraction, to yield a catalytically viable tyrosyl radical.
Much effort has been expended to mimic the oxidation chemistry of nonheme enzymes with iron(III) complexes with either hydrogen peroxide 13 -16 or tertbutylhydro peroxide 17-19 as the oxidant. By contrast, the reactivity of discrete, well
defined diiron(III) peroxo complexes derived from iron(II) precursors and 02 is
essentially unexplored. Given that sMMO utilizes a reductive 02 activation
pathway, it is desirable to track an oxidation reaction in a model system from the
dioxygen binding step, to formation of a high valent oxidant, and finally through
the substrate oxidation event. Such a study would provide invaluable insight into
the enzymatic mechanism, and as well as spawn the development of practical
oxidation catalysts. Here we provide a complete analysis of the reactivity of
diiron(III) peroxo complexes derived from the m-xylylenediamine
bis(kemp's
triacid)imide (H2XDK) ligand system. 20
Experimental Section
General
Considerations.
The
complexes
[Fe2(p-0
2 )(PXDK)(ji-
O2CPhCy)(O2CPhCy)(Bu-Im)2] (1) and [Fe2(j-02)(BXDK)(-02CPhCy)(0y)(O2CPhCy)(py) 21
(2) were prepared from 02 and the diiron(II) precursors at -77 'C according to an
established procedure. 20 Authentic samples of 3,3',5,5'-tetra-tert-butyl-1,1'-bi-2,2'phenol, 2 1 cyclopentylhydroperoxide,2 2 and 2-hydroxytetrahydrofuran,
23
were
synthesized according to the literature methods, and their purity was confirmed by
1H
NMR and/or GC and GC/MS analyses. Dioxygen (99.994%, BOC Gases) was dried
by passing the gas stream through a column of Drierite. Labeled dioxygen (95% 1802)
toluene, and THF reagents were purchased from Cambridge Isotope Laboratories,
Inc. The solvents were vacuum transferred from Na/benzophenone ketyl. All other
reagents were procured from commercial sources and used as received unless
otherwise noted. THF, cyclopentane, toluene, pentane, and Et 20 were distilled from
247
sodium benzophenone ketyl under nitrogen. Pentane, cyclopentane, isopentane, 1hexene,
and cyclohexene
were distilled from sodium
under nitrogen.
Dichloromethane, 1,2-dichloroethane, and pyridine were distilled from CaH 2 under
nitrogen. All air sensitive manipulations were carried out either in a nitrogen filled
Vacuum Atmospheres drybox or by standard Schlenk line techniques at room
temperature unless otherwise noted.
Physical Measurements. NMR spectra were recorded on a Bruker AC-250 or
Varian XL-300 spectrometer.
1H
NMR chemical shifts are reported versus
tetramethylsilane and referenced to the residual solvent peak. FTIR spectra were
recorded on a BioRad FTS-135 FTIR spectrometer.
GC and GC/MS. Analyses were carried out on a HP-5970 gas chromatograph
connected to a HP-5971 mass analyzer. Alltech Econo-cap EC-WAX capillary
columns of dimensions (15 m x 0.53 mm x 1.2 gm) and (30 m x 0.25 mm x 0.25 gm)
were used for GC and GC/MS studies, respectively, except for triphenylphosphine
and triphenylphosphine oxide, which were assayed with a HP-101 (12 m x 0.2 mm x
0.2 mm) capillary column. The following method was used to effect nearly all
separations: initial temperature = 50 'C, initial time = 10 min, and a temperature
ramp of 50-200 'C at 10 deg/min. The products were identified by comparing their
retention times and mass spectral patterns to those of authentic standards.
Integrations were acquired by FID detection run in parallel to mass spectrometry by
using an HP-3393 integrator. FID response calibration constants were measured by
running calibration curves with authentic samples and an internal standard, either
cyclopentanone or cyclohexanone.
For kinetic isotope or 1802 labeling studies, the ratio of isotopomers was
determined by mass spectral integration of each parent ion. The integration
response was assumed to be identical for the isotopomers.
248
Low-Temperature UV-vis Spectroscopy. Spectra were recorded on a HP8452A
diode array spectrophotometer by using a custom manufactured immersion dewar,
equipped with a 3 mL cell (1 cm pathlength) with quartz windows connected to a
14/20 female joint via a 10 cm long glass tube. A temperature of -77 'C was
maintained with a dry ice/acetone bath and monitored with a Sensortek Model
BAT-12 thermocouple thermometer.
Resonance Raman Spectroscopy. Raman data were acquired by using a
Coherent Innova 90 argon laser with an excitation wavelength of 647.1 nm and 65
mW of power. A 0.6-m single monochromator (1200 grooves/nm grating), with an
entrance slit of 100 gm, and a liquid nitrogen cooled-CCD detector (Princeton
Instruments, Inc.) were used in a standard backscattering configuration. A
holographic notch filter (Kaiser Optical Systems) was used to attenuate Rayleigh
scattering. Spectra of all samples were collected in toluene solution at -77 'C with the
same custom-manufactured dewar used to acquire low-temperature UV-vis spectra.
Solute concentrations were made as high as possible depending on the solubility of
the reduced sample, -20 mM in the best cases, to ensure an optimal signal-to-noise
ratio. High vacuum line techniques were used to transfer 1802 and to manipulate
the resulting samples. A total of 1000 scans each with a three second exposure time
were collected for each sample. Raman shifts were calibrated with toluene as an
internal standard. The data were processed by using CSMA software (Princeton
Instruments, Inc. Version 2.4A) on a Gateway 2000 computer, and the resulting
ASCII files were processed with Kaleidagraph (Abelbeck Software).
Synthetic Methods. General Procedures for Stoichiometric Reactions of 1 or 2
at -77 'C. All reactions were monitored by low-temperature UV-vis spectroscopy.
The dewar was equipped with a stir bar and loaded in the drybox with 5.0 mL of a
0.50-1.0 mM solution of the diiron(II) precursors of 1 or 2. The apparatus was topped
with a rubber septum, brought out of the box, placed under a positive N 2 pressure,
249
and cooled to -77 'C with a dry ice acetone bath. A spectrum was recorded, and then
the sample was subjected to a gentle purge of 02 at atmospheric pressure for 15 s,
after which time the peroxo complex 1 or 2 had formed to completion, as judged by
the blue color which had developed. Excess 02 was removed with a 5 min Ar purge
of the solution. Another spectrum was recorded, and then 200 gl of the test reagent
solution was added dropwise to a stirred solution of the peroxo complex, taking care
not to allow the peroxo solution to warm above -77 'C. For the CO 2 reactions, the gas
was bubbled gently through the solution of the peroxo complex over ~30 s. Note:
Owing to the low temperature, this procedure introduces a large excess of CO 2 to the
solution, and therefore considerable caution should be taken when venting the
solution upon warming so as to not build up a dangerous pressure level. The
resulting mixture was allowed to stir for 15-30 s, by which time a homogenous
solution had formed. Additional spectra were recorded, and the reaction was
monitored to completion, as judged by the complete decay of the peroxo charge
transfer band. The quantities of reagents and solvent used for each reaction are listed
in Table 4.1. UV-vis spectra are displayed in Figures 4.1-4.5 and 4.8-4.4.12.
General Procedures for Solvent Oxidation Studies. Samples were prepared in
the immersion dewar described above or in a round bottom flask sealed with a
rubber septum. All sample volumes were 5.0 mL. Peroxo complex 1 was generated
in the usual manner at -77 'C. It was stable for at least several hours at this
temperature, as judged by UV-vis spectroscopy, which afforded identical traces in all
the solvents. For thermolysis reactions carried out under argon, the peroxo solution
was degassed by carrying out three vacuum/Ar purge cycles and three freeze-pumpthaw cycles with liquid nitrogen, and then backfilled with 1 atm of Ar prior to
warming. Warming to room temperature over five min was accomplished by
removing the dry ice/acetone bath from the stirred solution. Warming over 2 h was
carried out by removing the excess dry ice while keeping the flask or UV-vis cell in
250
contact with the bath. Solutions incubated at low temperature for longer time
periods were placed in a -85 'C refrigerator. After addition of an internal standard,
the crude reaction mixtures were examined directly by GC and GC/MS analyses.
Intermolecular Kinetic Isotope Measurements. Peroxo complex samples (1.0
mM) were prepared in equimolar quantities of perdeutero or protio solvents, to a
total volume of 5.0 mL. Thermolyses were carried out over 5 min as described
above, and the crude reaction mixtures were analyzed by GC/MS.
Results and Discussion
Reactions of Peroxide Complexes 1 and 2 with Various Reagents at -77 'C. The
electronic spectra of the 1-alkylimidazole and pyridine complexes 1 and 2 were used
to monitor their reactivity toward three classes of substrates: oxygen-atom acceptors,
electrophiles/acids, and weak H-atom donors. Such a comparative analysis has been
used previously to characterize transition metal peroxo complexes, where the
reactivity pattern of the peroxide ligand depends on the Lewis acidity of the metal
ion and the mode of peroxo coordination. 24-26 In general, early transition metal ions
in high oxidation states render coordinated peroxide ligands electron deficient such
that they typically undergo oxygen-atom transfer reactions to acceptors such as
phosphines and olefins. These reactions become more favored thermodynamically
as the substituents bound to the reacting substrate functionality are more electron
releasing. By contrast, low-valent, late-metal peroxo adducts usually behave as
nucleophiles, undergoing addition reactions to electrophiles such as C0 2, acyl
chlorides, or electron-deficient olefins. In addition, these electron rich peroxo
adducts will react with acids to afford hydroperoxo complexes or they may react with
an additional acid equivalent to liberate H2 0 2 . Peroxo complexes may also display
radical character and react with weak hydrogen atom donors such as isopropyl CH 2 7, 28 and phenolic O-H 24 ,25 bonds. Peroxo 0-0 bond cleavage may occur prior to
251
hydrogen atom abstraction in these reactions, as has been demonstrated in a related
bis(g-oxo)dicopper
system. 2 9 - 3 1
Moreover,
the
distinction
between
nucleophilic/basic versus radical peroxo character can be probed with phenols since
deprotonation usually leads to phenoxide coordination, 26 whereas hydrogen atom
abstraction provides a phenoxyl radical. With the appropriate aryl substitution, such
a species can be identified as the 2,2'-biphenol-coupled product. 24,32
Stoichiometric reactions were conducted by generating peroxo complex 1 or 2
in solution at -77 'C, followed by thorough removal of excess 02 with Ar
purge/dynamic vacuum cycles and then addition of the reagent. Reactions were
monitored by UV-vis spectroscopy. These studies are summarized in Scheme 4.1.
No reaction was observed for peroxo adducts 1 or 2 with triphenylphosphine or 2cyclohexen-l-one, an outcome which suggests that this class of peroxo complexes
has no electrophilic character, even toward electron-poor olefins. Similarly,
exposure of either peroxo complex to the weak H-atom donor dimethylbenzylamine
afforded no reaction.
Treatment of the 1-butylimidazole peroxo complex 1 with 1.0 equiv of 2,4-ditert-butylphenol resulted in a color change from purple to deep royal blue within 30
s. By contrast, peroxo 2 did not react with the phenol under similar conditions. UVvis spectral studies of both of these reactions were carried out, the results of which
are displayed in Figure 4.1-4.2. The product spectrum for 1 + phenol persists for > 2 h
at -77 'C, but decays rapidly upon warming to room temperature. No 2,2'-biphenol
coupled product was detected by GC/MS, as judged by comparison of the product
chromatogram to that of pure 2,2'-biphenol, but H 20 2 was detected qualitatively.
These facts, coupled with the metastable nature of the product and the resemblance
of its UV-vis spectrum to that of 1 suggested that a diiron(III) phenoxidehydroperoxide complex might have been formed through deprotonation of the
phenol with the diiron(III)-bound peroxide. The resulting charge transfer band at
252
620 nm (e = 1400 M-lcm
-1 )
is considerably blue-shifted from those of known
hydroperoxo complexes, however, [FeIII(N4Py)(OOH)(MeCN)](C10
nm, e = 1100 M-lcm-1) 33 and [Fe(TPA)(OOH)](C10
4 )]
2+
4 )2
( max = 458
(Xmax = 538 nm).1 3 Moreover,
reactions with less electron-rich phenols such as the parent compound and
pentafluorophenol exhibited UV-vis bands blue shifted of that obtained for the 2,4di-tert-butylphenol product (Figures 4.3-4.4). Both of these facts make it more likely
that the product UV-vis feature is due to a phenoxide-to-iron(III) charge transfer.
Resonance Raman studies were conducted to probe further the fate of the
peroxide complex 1 upon treatment with 2,4-di-tert-butylphenol. Peroxo species
were prepared with 1602 or 1802, and each was treated with 1.1 equiv of the phenol.
Spectra before and after the reaction are displayed in Figures 4.5 and 4.6. For the 1602
sample, the v( 16 0-
16 0)
band at 864 cm - 1 disappears almost entirely upon addition of
the phenol, and two new bands appear at 750 and 913 cm - 1 . The v( 18 0-
18 0)
band also
diminishes when phenol is added, as judged by the narrowing and shifting of the
peak at -825 cm - 1 , which is composed of the peroxo band and one assigned to
toluene (see Chapter 3, Figures 3.13-3.14). The same two new peaks that were
observed when phenol was added to the 1602 sample also appear in the 1802
spectrum, indicating that neither can be ascribed to a hydroperoxide or peroxide
species. These features are therefore assigned to phenol vibrations which are
resonance enhanced by the phenoxide-to-iron charge transfer band. A new v(O-O)
band may be obscured by the toluene peaks, but none was observed after carrying out
solvent subtraction routines.
Irrespective of the identity of the products, this set of experiments shows that
1 behaves as a basic, as opposed to a hydrogen atom abstracting, peroxo species. The
fact that 2 does not react at all with 2,4-di-tert-butylphenol further supports this
conclusion. Compared to pyridine, the more basic 1-alkylimidazole groups impart
additional electron density to the iron centers, which is in turn transmitted to the
253
peroxide. The large discrepancy in the pKa values for 1-butylimidazole (-6.8)
compared to phenol (~10.0) 34 makes proton transfer to the 1-alkylimidazole ligand
highly improbable.
Two other proton donors were investigated to probe further the character of
the peroxide ligands in 1 and 2. Treatment of 1 with 1.1 equiv of 2,4,6-tri-tertbutylphenol provided no reaction, as judged by UV-vis spectroscopy (Figure 4.7).
Apparently proton transfer does not occur in this case because the sterically
encumbered phenol blocks access to the peroxide ligand. Alternatively, the
deprotonated phenol may be too hindered to bind to the iron center(s). A carboxylic
acid was used to determine whether a hydroperoxo complex could be stabilized by
an additional hindered carboxylate ligand and to see if the less basic pyridine peroxo
complex 2 could be protonated. Treatment of peroxo complex 1 with 1.1 equiv of 1phenylcyclohexylacetic acid was accompanied by decomposition at -77 'C within 1530 s (Figure 4.8), yielding intractable products following workup at room
temperature. Like all the phenol reactions, H 20 2 was detected qualitatively in the
crude decomposed mixtures. Peroxo 2 was completely unreactive toward the
carboxylic acid, an outcome which further illustrates the vastly different electronic
properties that are imparted to the two peroxo ligands solely by the choice of Ndonor ligand.
Electrophilic reagents were examined to probe the nucleophilicity of the
peroxo complexes. Exposure of 1 -77 oC to a large excess of CO 2 resulted in decay of
the peroxide-to-iron charge transfer band at within 15 s (Figure 4.9). As with other
peroxo complexes that react with CO2, this reaction probably generates a
peroxycarbonate species which decomposes to an iron(III) carbonate complex(es),
although nothing tractable was isolated from the reaction mixture. Consistent with
the protonolysis studies, 2 was unreactive toward CO 2 over the course of 2 h of
monitoring the reaction by UV-vis spectroscopy (Figure 4.10).
254
Finally, the behavior of 1 toward reductants was examined to obtain an
estimate of its reduction potential. No reaction was observed with ferrocene or
pentamethylferrocene (Figure 4.11), but treatment with cobaltocene induced a rapid
decay of the peroxo UV-vis band (Figure 4.12). The cobaltocenium cationic product
could not be identified because intense features in the higher energy visible region
dominated the spectrum. Assuming this compound donates an electron to the
peroxo complex in a 1:1 stoichiometry, then the reduction potential of 1 is estimated
to be between that of Cp2*Fe and cobaltocene, -0.59 and-1.33 mV, respectively vs.
Cp 2Fe+/Cp 2 Fe. 35 This value attests to the stability of the diiron(III) peroxo species
toward hydrogen atom donors and dioxygen dissociation, since both processes
would require reduction of one or both Fe(III) ions. In particular, it provides at least
a partial explanation as to why peroxo species 1 deprotonates 2,4-di-tert-butylphenol
instead of abstracting a hydrogen atom from this reagent.
Thermolysis Reactions Leading to Solvent Oxidation. Solutions of peroxo
complexes 1 or 2 rapidly decay when warmed above - 65 'C, changing from purple
and midnight blue, respectively, to an orange brown color which is characteristic of
g-oxodiiron(III) complexes. Several mechanisms could account for this decay. The
most well documented of such a reaction in diiron(III) peroxo chemistry is a
bimolecular decomposition accompanied by extrusion of 0.5 equiv of 02 per diiron
complex, affording oxo-bridged Fe(III) products. 36,37 This process could not account
for the entire decomposition of 1 or 2 because manometric studies indicated either
that 02 was not released during decay or that in solvents such as THF and CH 2C12,
up to an additional equiv of dioxygen was consumed. 20 Such a result might be
explained a priori by ligand oxidation, but a thorough 1H NMR and GC/MS analysis
of the organic components revealed no oxidized ligands following acid dissociation
and extraction of the decomposition products. Instead, solvent oxidation products
were identified in the reaction mixtures for several different solvents. A detailed
255
analysis of those reactions for 1 was undertaken because its butyl and propyl groups
make it soluble in a wide variety of hydrocarbons. Table 4.2 summarizes the results
of this initial survey.
These studies defined the scope of the oxidation process. Substrates with
particularly weak C-H bonds 34 such as THF (92 kcal/mol), cyclohexene (allylic C-H
= 85 kcal/mol), and toluene (85 kcal/mol) afforded y-butyrolactone and 2hydroxytetrahydrofuran, 2-cyclohexen--ol, 2-cyclohexen-l-one, and cyclohexene
oxide, and benzaldehyde, respectively, in modest yields based on 1. Dichloroethane,
identified qualitatively as a product of peroxo decay in CH 2C12 solutions, was formed
by C-C1 bond homolysis. Solvents with high C-H bond strengths such as isopentane
(95 kcal/mol), and pentane (98 kcal/mol) were completely unreactive. Cyclopentane,
with an intermediate C-H bond strength (94.5 kcal/mol), provided a small amount
of product.
A key to understanding this chemistry is provided by the product distribution
for each substrate. For cyclohexene, only allylic oxidation products were produced in
appreciable quantities. This result contrasts with that for sMMO, early transition
metal peroxo complexes, and many terminal oxo complexes, which all afford the
epoxide as the major or exclusive product. For oxidations at saturated C-H bonds,
ketones are favored over alcohol products, whereas sMMO affords alcohols
exclusively.
To investigate the mechanism in more detail, we chose to focus on
cyclopentane oxidation. This solvent is readily purified and not susceptible to
autoxidation in air for months at room temperature. Cyclohexene and THF, on the
other hand, autoxidize after -12 h in air, judging by GC/MS. From a practical
standpoint its higher C-H bond strength makes cyclopentane a more attractive
target.
256
Table 4.3 lists a series of conditions designed to probe the oxidation
mechanism of cyclopentane. Entries 1-3 reveal that yields of ketone and alcohol are
unaffected by the warming rate, or reaction atmosphere, or peroxo concentration,
providing in each case the same small quantities of ketone and alcohol in a 2.5:1
ratio. When decomposed reaction mixtures were allowed to stand in air for
extended periods of time (entries 6-8), however, a slow but steady production of
additional product resulted, as determined by analyzing aliquots of the reaction
mixture by GC/MS on a daily basis. After three weeks the total yield of oxidized
products based on the original [1] was 250%, but the ketone:alcohol ratio remained
invariant over this time period. The latter observation suggests that the entire
oxidation process proceeds through a common mechanism, from the initial
warming of the peroxo solution and throughout prolonged incubation in air at
room temperature. An aliquot of the long-term reaction was removed after 1 day
(entry 8) and treated with a 50-fold excess of 2,4,6-tert-butylphenol, which complete
quenched product formation. Moreover, when solutions of 1 were warmed in the
presence 1.0 equiv of this phenol, with which it does not react at -77 °C (vide supra),
no oxidized products were observed either immediately after the reaction or upon
standing in air for several days.
An intermolecular kinetic isotope effect (KIE) was not measured for
cyclopentane
oxidation because the perdeutero isotopomer is prohibitively
expensive. Alternatively, we carried out measurements using THF and toluene as
solvents, which afforded kH/kD values of 6.2 and 7.8, respectively (Figures 4.15-4.16).
These values may be compared to the intramolecular KIE values of 2-3 for Gif
cyclohexane and adamantane oxidations,38 and 1.0 for sMMO. 39
The ability of phenol to quench product formation indicates that a free
radical, non-metal based autoxidation mechanism is most likely occurring for this
system. An example of such a mechanism is illustrated by eqs 2-5 for oxidation at a
257
secondary
carbon
Initiation
Propagation
Termination
atom.
This
.26
In.+ R2 CH2 -
R2 CH- + 02
well
hydrocarbon
oxidation
InH + R 2CH.
(2)
R 2 CHOO-
(3)
R2 CH- + R2 CHOOH
--
R2 CHOO- + R2CH
2
2 R 2CHOO.
RH
2 UO4
-
known
2
---
R2CHOH + R(CO)R + 02
(4)
(5)
process is initiated by hydrogen atom abstraction to generate an alkyl radical, which
is trapped with dioxygen. The resulting alkyl peroxy radical then reacts with another
equivalent of substrate, and the chain is propagated. Chain termination occurs when
two alkyl peroxy radicals combine, and this resulting species then rearranges to
afford dioxygen, ketone, and alcohol. Decomposition of the resulting alkyl
hydroperoxide to ketone and alcohol can be catalyzed by iron salts via the HaberWeiss cycle (eqs 6-7).40,41 The resulting alkoxy radical reacts with substrate to yield
alcohol (eq 8), and the alkyl peroxy radical can decompose as indicated in eq 5.
Fe(ll) + R2 CHO 2 H----Fe"'(OH) + R2 CHO 2 H
-
RO- + R2 CH 2 ----
R 2 CHO. + Fe'(OH)
(6)
R 2 CHOO. + Fel"
(7)
R2CH. + ROH
(8)
The reaction mixtures were analyzed by 1 H NMR and GC/MS to determine
whether a significant concentration of cyclopentylhydroperoxide builds up over the
course of the extended reactions. No
1H
NMR resonances or GC/MS peaks
attributable to this species were identified upon comparing the data to that obtained
for a pure sample prepared independently. A peroxo sample was also warmed in the
presence of 10 equiv of PPh 3 to trap any intermediate cyclopentylhydroperoxide,
which would afford triphenylphosphine oxide and alcohol. This procedure neither
changed the overall yield nor altered the ketone:alcohol ratio, suggesting that if the
hydroperoxide is formed it decomposes exceedingly rapidly.
258
Perhaps the most interesting issue for this system is the role of 1 in the
autoxidation chemistry. For reactions conducted under Ar, the peroxo is presumably
the source of free 02, whereby some is released from the peroxo upon warming. In
addition, it is highly probable that a metal-bound oxygen species is involved in the
initiation step. This reaction involves direct hydrogen atom abstraction by the
diiron(III) peroxide, affording a Fe(II)Fe(III) hydroperoxo complex and an alkyl
(eq 8).
radical
[FelI 2 (,-0
former
The
could then eliminate
2 )(XDK)(O 2CPhCy) 2 (Bu-Im) 2 1
a hydroxyl radical
+ C5Hlo
[FelIFe lI(OOH)(XDK)(O 2 CPhCy)2 (Bu-Im) 2 ] + C5 H9
(9)
[FellFe'll(OOH)(XDK)(O 2CPhCy) 2 (Bu-Im) 2]
[Fe 211(-O)(XDK)(O
2 CPhC) 2 (Bu-Im) 2 ]
+ OH.
(10)
and a (g-oxo)diiron(III) product (eq 9). This particular sequence of events is unlikely,
however, since 1 displays no propensity to abstract a hydrogen atom from even
weak H-atom donors such as phenol (O-H bond strength = 88 kcal/mol) 34 .
Alternatively, the peroxo complex may convert to a new intermediate that is capable
of the hydrogen atom abstraction reaction. One possibility is a dioxodiiron(IV)
species having the same metal oxidation states as sMMO-Q but exhibiting a much
different pattern of reactivity (eq 11). Another possibility is a bimolecular decay,
whereby
some of the peroxo complex
decays by releasing
02 upon
0-0 bond
homolysis
[Felll2 (-0
2)(XDK)(O 2 CPhCy) 2 (Bu-Im) 2 ]
A
[Fe2'V(0)2(XDK)(02CPhC)2(Bu-Hm)21.
[Fe"'l2 (R-0
2 )(XDK)(O 2 CPhCy) 2 (Bu-Im) 2]
1
C5 H9
(11)
11)
C5H9-
A
[Fe 2 (XDK)(O 2 CPhCy) 2 (Bu-Im) 2 1
1, H+
(12)
OH. +
Fe(III) Prods.
259
warming, and the resulting reducing equivalents are then used at a diiron(III)
peroxide to effect Fenton chemistry, perhaps with trace water serving as a proton
source to generate a hydroxyl radical (eq 12).
An important conclusion to be drawn from the cyclopentane oxidation
studies is that we have not accessed the manifold of reactivity used by the diiron
centers in sMMO in terms of substrate scope, product selectivity, or the oxidation
mechanism. Studies of the enzyme with radical clock substrate probes and chiral
ethane have provided evidence against a discrete radical intermediate, having a
lifetime greater than - 10-13 s.42,43 For a functional model system to duplicate the
enzymatic chemistry, metal-based oxidants which formally abstract a hydrogen atom
from a substrate molecule must be avoided. Not only might such a reaction lead to
undesired radical chain autooxidation chemistry, but also because it would simply
that the model has not matched the composition and structure of the key enzymatic
oxidant.
Recent X-ray studies of resting state MMOH and EXAFS studies on
intermediate Q provide some insight into why the diiron XDK system may not be
able to mimic the enzymatic chemistry and suggest new design strategies for
improved functional models. In the resting enzyme, only one carboxylate ligand
bridges the diiron center. The short Fe...Fe distance of 2.5 A observed for
intermediate
Q
cannot
be
accommodated
by
a syn syn
bidentate
bis(carboxylate)bridged core, and it is unlikely that the rigid XDK ligand system
possesses the flexibility to undergo the carboxylate shift44 required to convert peroxo
adducts 1 or 2 into Q-like diiron(IV) complexes. Alternatively, ligands which
provide a single syn syn bidentate carboxylate bridge while maintaining a rigid
dinucleating framework may provide ideal balance for converting a peroxo adduct
into a Q-like species. Efforts to prepare such complexes are currently underway in
this laboratory.
260
Conclusions
The reactivity properties of diiron(III) peroxo complexes 1 and 2 have been
fully elucidated. These adducts behave as nucleophilic/basic peroxides, exhibiting no
propensity to serve as oxygen atom donors, even for potent acceptors such as
triphenylphosphine.
The
1-butylimidazole
ligands
in
1 enhance
the
nucleophilicity/basicity of the peroxo compared to the pyridine analog, probably
because the former ligand is a superior a-donor. This feature imparts more electron
density to the iron centers, which in turn is transmitted to the peroxo ligand.
Thermolysis of the peroxo adducts in a variety of media results in solvent oxidation,
providing ketone and alcohol products in modest yield based on the complex. A
detailed analysis of cyclopentane oxidation provided evidence for a radical chain
autoxidation mechanism, a reactivity manifold which does not mimic the
hydrocarbon oxidation chemistry of sMMO. Future efforts are aimed at preparing
diiron(III) peroxo complexes with mono(carboxylate)-bridged structures, a design
aspect which may facilitate conversion to a Q-mimic and allow access to the
enzymatic hydroxylation pathway.
261
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Table 4.1. A summary of reagents and solvents used for the stoichiometric reactions.
Reagent
Reagent Quantity
Peroxo
Quantity of Diiron(II)
Solvent (5.0 mL)
Precursor (mg, tmol)
Triphenylphosphine
6.0 mg, 23 jamol
1
5.0, 3.3
THF
2-Cyclohexen-l-one
6.0 mg, 23 pmol
1
6.5, 4.3
THF
Dimethylbenzylamine
10 ptl, 66 gmol
1
10, 6.6
2,4-Di-tert-Butylphenol
1.0 mg, 4.9 pmol
1
7.4, 4.9
Et 2 0
THF
2,4-Di-tert-Butylphenol
1.0 mg, 4.9 .tmol
2
Phenol
0.5 mg, 5.3 Ipmol
1
7.0, 4.1
6.8, 4.5
CH 2C12
THF
Pentafluorophenol
0.7 mg, 3.5 pmol
1
4.8, 3.2
THF
5 tl, 5 mol
1
6.4, 4.2
Cyclopentane
1.0 mg, 4.7 ipmol
1
6.5, 4.3
Toluene
CO 2
excess
1
7.4, 4.9
Et 2 0
CO 2
Pentamethylferrocene
excess
1.4 mg, 4.4 p.mol
2
1
7.0, 4.1
6.0, 4.0
CH 2C12
THF
Cobaltocene
0.8 mg, 4.4 jnol
1
6.0, 4.0
THF
2,4,6-Tri-tert-Butylphenol
1-Phenylcyclohexylcarboxylic
Acid
265
Table 4.2. A survey of solvent oxidation reactions mediated by peroxo 1.
-80 oC -- r.t.
over 5 min
under Ar
Solvent Oxidation Products
Analyzed By GC-MS
+
(i-O)Fe(Ill) Products
PXDK
[1] = 1 mM
Products (%Yield Based on 1)
Solvent
OH(
0
O
C
+
==
(20)
(5)
CIl
(Yield Not Determined)
0H 201 2
~
-
C -
(20)
0
0
H
0-
(2)O
(5)
OH
0
1+
(14)
(29)
No Reaction
No Reaction
No Reaction
(< 1)
Table 4.3. Cyclopentane oxidation reactions carried out with peroxo 1 under a set of experimental conditions
designed to probe the mechanism.
0
[Fe 2(-0 2)(PXDK)(0 2CPhCy) 2(Bu-m) 2]
Entry
Atmosphere
Temp (oC)/Heating Rate
Conc. (mM)
+
+ Fe(III) products
Yield (%)
Additives (Equiv)
-one
Ar or 02
None
-77 -- r.t. over 5 min
5
-77 -> r.t. over 2 h
-85 for 3 days
Ar or 02, then
-77 -- r.t. over 5 min
0.12
-77 -4 r.t. over 5 min
11.2
-77
1.2
air
->
r.t. over 5 min
then r.t., 24 h
-77
-
170
r.t. over 5 min
then r.t., 3 weeks
-77
Ar or 02
-
r.t. over 5 min
2,4,6-t-Bu-Phenol
then r.t., 3 weeks
(10) after 24 h
-77 - r.t. over 5 min
2,4,6-t-Bu-Phenol (10)
-77 -4 r.t. over 5 min
PPh 3 (1.0)
-77 -4 r.t. over 5 min
HO 2 CPhCy (10)
or H 2 0 (10)
-ol
267
N.R.
Cp2Co + (?)
+ Fe decomposition
products
N.R.
PPh 3
N,
BnNMe 2
N.R.
Fe.
0
,
\ 0 N/\
C02
Fe
Fe(lll)-CO3
Products
N
PXDK
H0 2CPhCy
2,4-Di-t-Bu-Phenol
2,4,6-tri-t-Bu-Phenol
OFeil
-0 2 CPhCy- + H20 2
+
H20 2
t-Bu
mixture of Fe"'-phenolXDK products
Scheme 4.1.
N.R.
268
1500
Peroxo (1) + 1.0 Equiv 2,4-Di-t-Butylphenol
at -77 OC
=620(1400)
Peroxo (1
Phenol Prod.
Decaying
0-1000
500 -
300
R.T. Product
400
500
600
700
800
X (nm)
Figure 4.1. Electronic absorption spectrum of 1 in THF at -77 'C (0.98 mM), 1.0 equiv
of 2,4-di-t-butylphenol added, and six traces qualitatively tracking the decay of the
phenol product upon thermolysis from -77 oC to room temperature.
269
1500
Peroxo (2) + 1.2 Equiv
2,4-Di-t-Butylphenol
1000
E
500 -
-
Reduced
Complex
0
300
400
600
500
700
800
X (nm)
Figure 4.2. Electronic absorption spectrum of 2 in CH 2C02 at -77 'C (0.82 mM), 1.2
equiv of 2,4-di-t-butylphenol added, and an additional trace monitoring this
reaction.
270
2500
Peroxo (1) + 1.2 Equiv
Phenol at -77 OC
A
= 546 (2100)
2000 -\
Phenol
1500
-
E 1500
Peroxo (1)
1000
500 -
R.T. Product --
0
300
400
600
500
700
800
k (nm)
Figure 4.3. Electronic absorption spectrum of 1 in THF at -77 'C (0.90 mM), 1.2 equiv
of phenol added, and six traces qualitatively tracking the decay of the phenol product
upon thermolysis from -77 'C to room temperature.
271
3500
3000
2500
2000
E
o
r
U.
1500
1000 -
500 0
_
Reduced Complex
-
300
400
600
500
700
800
X (nm)
Figure 4.4. Electronic absorption spectrum of 1 in THF at -77 'C (0.63 mM), 1.1 equiv
of pentafluorophenol added, and three additional traces tracking the decay of the
phenol product upon thermolysis form -77 'C to room temperature.
272
5.50 105
5.00 105
3 4.50 10 s
o
4.0010s
.
3.50 105
3.00 105
700
750
800
850
900
Raman Shift (cm "1)
950
1000
750
800
850
900
Raman Shift (cm-1)
950
1000
5.50 105
5.00 10s
4.50 105
- 4.00 10s
o
3.50 105
3.00 10 5
2.50 105
700
Figure 4.5. Resonance Raman spectra obtained with 647 nm excitation on fluid
toluene solutions (-80 °C) of: (A) [Fe2( 160 2)(PXDK)(O 2CPhCy) 2 (Bu-Im) 2 1 (1-1602), (B)
1-1602 + 1.1 equiv of 2,4-di-tert-butylphenol.Peaks marked with an asterisk and
those off scale are due to toluene.
273
A.
1.60 106
1.50 106
1.40 106
S1.30 106
0
-2 1.20 106
0
1.10 106
1.00 106
9.00 10 5
I
8.00 105
700
750
I
I
800
I
850
900
Raman Shift (cm -1)
I
950
1000
B.
8.00 105
7.50 105
750 cm "'
5
7.00 10
, 6.50 105
C.
5
-2 6.00 105
0
S5.50 10
5.50
cm 1
1913
5.00 105
4.50 105
4.00 105
700
I
I
750
800
I
I
900
850
Raman Shift (cm1 )
950
I
1000
Figure 4.6. Resonance Raman spectra obtained with 647 nm excitation on fluid
toluene solutions (-80 oC) of: (A) [Fe 2 (18 0 2 )(PXDK)(O 2 CPhCy) 2 (Bu-Im) 2] (1-1802) and
(B) 1-1802 + 1.1 equiv of 2,4-di-tert-butylphenol. Peaks marked with an asterisk and
those off scale are due to toluene.
274
2000
Peroxo (1) + 1.1 Equiv.
2,4,6-Tri-t-Butylphenol
1500
E
o 1000
Reduced
Complex
500 -
300
R.T. Product
400
500
600
700
800
X (nm)
Figure 4.7. Electronic absorption spectrum of 1 in cyclopentane at -77 oC (0.84 mM), 2
equiv of 2,4,6-tri-tert-butylphenoladded, and one additional trace showing the
decomposition product obtained upon thermolysis from -77 oC to room
temperature.
275
1500
--
Peroxo (1)
1000
E
500
Peroxo(1) + 1.1 Equiv
H02CPhCy
--®1
0
300
Reduced Complex
I
I
I
I
400
500
600
700
800
X(nm)
Figure 4.8. Electronic absorption spectrum of I in toluene at -77 °C (0.86 mM), and
after 1.1 equiv of HO2CPhCy was added. Decomposition to the room-temperature
stable product occurred at -77 oC.
276
3200 2800
2400
2000 -
Peroxo (1)
oR 1600
1200
Peroxo Decay After
CO2 Addition
800 400 R.T. Product
300
400
t
500
600
700
800
X (nm)
Figure 4.9. Electronic absorption spectrum of 1 in Et 2 0 at -77 'C (0.98 mM) and ten
traces qualitatively tracking the decay of the peroxo upon addition of CO 2 .
Decomposition to the room-temperature stable product occurred at -77 'C.
277
2000
Peroxo (2) + excess CO
2
1500
E
o 1000
500
.4-
Reduced Complex
0
300
400
500
600
700
800
X (nm)
Figure 4.10. Electronic absorption spectrum of 2 in CH 2C12 at -77 oC (0.82 mM) in the
presence of excess CO 2.
278
2000
Peroxo (1) + 1.1 Equiv
Cp2 *Fe
1500
E
O
1000
500
0
300
I
I
I
I
400
500
600
700
800
X (nm)
Figure 4.11. Electronic absorption spectrum of 1 in Et 20 at -77 oC (0.79 mM), and in
the presence of 1.1 equiv of Cp 2*Fe.
279
2000
Peroxo (1) + 1.1 Equiv.
C p2Co at -77 oC
1500 -
E
Peroxo
1000 -
Decay
500
I
0 1I
300
400
600
500
700
800
X (nm)
Figure 4.12. Electronic absorption spectrum of 1 in THF at -77 'C (0.79 mM), and after
1.1 equiv of Cp2Co was added. Decomposition to the room-temperature stable
product occurred at -77 oC and it was followed qualitatively.
280
o
O
o
o
U
U
U,
0
O
0
(U
IN
-
-
Figure 4.13. A representative GC chromatogram for cyclopentane oxidation reactions
with peroxo 1. The sample used for this run was derived from a crude reaction
mixture. The cyclohexanone is an internal standard.
,,€
mixture. The cyclohexanone is an internal standard.
281
7.806
cyclopentanone
16.840 2-hydroxytetrahydrofu ran
18.835
19.866
y-butyrolactone
2-hydroperoxytetrahydrofuran
Figure 4.14. A representative GC chromatogram for THF oxidation reactions with
peroxo 1. The sample used for this run was derived from a crude reaction mixture.
The cyclopentanone is an internal standard.
282
Nbundance
M+
1200000
=
86
20.41
1000000
800000
kH/kD
600000
=
6.2
400000
M + = 92
20.38
200000
0
rime-->
20.25
20.30
20.35
20.40
20.45
20.50
Figure 4.15. A GC-MS chromatogram for the parent ions of h 6 -and d 6 - ybutyrolactone, a competitive deuterium isotope effect measurement for THF
oxidation by peroxo 1.
283
M+ = 106
18.72
50000
40000
kH/kD = 7.8
30000
20000-
M+= 112
18.78
10000
0
inme-->
18.70
18.75
18.80
18.85
Figure 4.16. A GC-MS chromatogram for the parent ions of h 6-and d6- benzaldehyde,
a competitive deuterium isotope effect measurement for toluene oxidation by
peroxo 1.
284
Biographical Note
The author was born in Madison, WI on April 6, 1970. After spending a short
amount of time there and in Illinois, California, and Ohio, he resided in Racine, WI
for the remainder of his primary and all of his secondary education, which
culminated in graduation from J. I. Case High School in 1988. From there he went
on to the University of Minnesota-Twin Cites, where Professor William B. Tolman
provided him with such remarkable undergraduate research opportunities in
chemistry that he decided to pursue his doctorate in this field instead of medicine.
Following his graduate studies at MIT, the author plans to work as a postdoctoral
fellow with Professor Erick M. Carreira at the California Institute of Technology.